April 20 in History

Baldwin III (1130 – 10 February 1163) was the king of Jerusalem from 1143 until his death. Although he only took up sole rule in 1152 and died young, he was the longest-reigning of the 12th-century kings of Jerusalem. He expanded the borders of the kingdom, paved the way for the later kings' attempts to conquer Egypt, and acted as the defender of the other crusader states in the Levant. Baldwin was the eldest son of Queen Melisende and King Fulk. Melisende's father, King Baldwin II, conferred the Kingdom of Jerusalem on the young Baldwin and his parents in 1131, but Baldwin III was only crowned after the death of his father in 1143. Baldwin initially reigned alongside his mother, who was the true ruler of the kingdom. He attempted to assert himself in warfare even before reaching the age of majority at 15, but after an initial military success in quelling a popular rebellion at Wadi Musa in 1144, he suffered a defeat in the Hauran and participated in the Second Crusade's failed attempt to capture Damascus in 1148. Baldwin took on the traditional responsibility of the kings of Jerusalem to look after the Principality of Antioch and the counties of Edessa and Tripoli. In 1149 he intervened in Antioch after the death of its prince, Raymond of Poitiers, and in 1150 arranged the sale of the last of the Edessan fortresses to the Byzantine Empire. His relationship with his mother soured as he strived for a greater role in the government and she sought to marginalize him. Matters came to a head in April 1152, when he deposed her in a swift military action. He was soon called on to settle the affairs of the County of Tripoli after the assassination of Count Raymond II. In 1153, Baldwin conquered the vital city of Ascalon and welcomed the marriage of his cousin Constance, widow of Prince Raymond, to Raynald of Châtillon. After nearly being killed or captured in a battle against the Aleppan ruler Nur ad-Din in 1157, he established an alliance with Emperor Manuel I Komnenos and married the emperor's niece Theodora. Baldwin and Manuel developed a close relationship, marred only by the latter's failure in the early 1160s to marry Baldwin's cousin, Melisende of Tripoli. Baldwin took up rule in Antioch once more in 1161 after Turkic forces captured Raynald. Baldwin died of an illness in 1163, having produced no children with Theodora, and was succeeded by his brother, Amalric.

The Sapienza University of Rome (Italian: Università degli Studi di Roma "La Sapienza"), also known as La Sapienza (The Wisdom or The Knowledge), is a public research university located in Rome, Italy. It was founded in 1303 and is one of the world's oldest universities. With over 110,000 students, it is also the largest university in Europe. Due to its size, funding, and numerous laboratories and libraries, Sapienza is a global major education and research centre. The university is located mainly in the Città Universitaria (University city), which covers 44 ha (110 acres) near the Campo Verano cemetery, with different campuses, libraries and laboratories in various locations in Rome. Sapienza was founded on 20 April 1303 by decree from Pope Boniface VIII as a Studium for ecclesiastical studies under more control than the free-standing universities of Bologna and Padua. In 1431 Pope Eugene IV completely reorganized the studium and decreed that the university should expand to include the four schools of Law, Medicine, Philosophy, in addition to the existing Theology. In the 1650s the university became known as Sapienza, meaning "wisdom" or "knowledge", a title it still retains. After the capture of Rome by the forces of the Kingdom of Italy in 1870, La Sapienza rapidly expanded as the chosen main university of the capital of the newly unified state. In 1935 the new university campus, planned by Marcello Piacentini, was completed. Sapienza teaches and conducts research in all pure and applied sciences and humanities. Sapienza houses 50 libraries with over 2.7 million books, most notably the Alessandrina University Library, built in 1667 by Pope Alexander VII, housing 1.5 million volumes. In addition it has 19 museums, a botanical garden, and three university hospitals. Sapienza's alumni includes 10 Nobel laureates, Italian prime ministers, one pope, presidents of the European Parliament and European Commissioners, as well as several notable religious figures, supreme court judges, and astronauts. Since June 2026, it has an international campus in Wuhan, China, focused on law and economics According to many international rankings, including Shangai Ranking, it is the ranked 1st Italian University and 1st in Southern Europe.

The Bahri Mamluks, sometimes referred to as the Bahri dynasty, were the rulers of the Mamluk Sultanate of Egypt from 1250 to 1382, following the Ayyubid dynasty. The members of the Mamluk ruling class were purchased as slaves (mamluks) and manumitted, with the most powerful among them taking the role of sultan in Cairo. While several Bahri Mamluk sultans tried to establish hereditary dynasties through their sons, these attempts were ultimately unsuccessful, with the role of sultan often passing on to another powerful Mamluk.

Vädersolstavlan (Swedish for 'The Sundog Painting'; ) is an oil-on-panel painting depicting a halo display, an atmospheric optical phenomenon, observed over Stockholm on 20 April 1535. It is named after the sun dogs (Swedish: Vädersol, lit. 'weather sun') appearing on the upper right part of the painting. While chiefly noted for being the oldest depiction of Stockholm in colour, it is arguably also the oldest Swedish landscape painting and the oldest depiction of sun dogs. The original painting, which was produced shortly after the event and traditionally attributed to Urban målare ("Urban [the] Painter"), is lost, and virtually nothing is known about it. However, a copy from 1636 by Jacob Heinrich Elbfas held in Storkyrkan in Stockholm is believed to be an accurate copy and was until recently erroneously thought to be the restored original. It was previously covered by layers of brownish varnish, and the image was hardly discernible until carefully restored and thoroughly documented in 1998–1999. The painting was produced during an important time in Swedish history. The establishment of modern Sweden coincided with the introduction of Protestantism and the break-up with Denmark and the Kalmar Union. The painting was commissioned by the Swedish reformer Olaus Petri, and the resulting controversies between him and King Gustav Vasa and the historical context remained a well-kept secret for centuries. During the 20th century the painting became an icon for the history of Stockholm and it is now frequently displayed whenever the history of the city is commemorated.

Oliver Cromwell was an English statesman and soldier, widely regarded as one of the most important figures in British history. He came to prominence during the Wars of the Three Kingdoms, initially as a senior commander in the Parliamentarian army and later as a politician. A leading advocate of the execution of Charles I in January 1649, which led to the establishment of the Commonwealth of England, Cromwell ruled as Lord Protector from December 1653 until his death in September 1658.

General at Sea Robert Blake (27 September 1598 – 7 August 1657) was an English naval officer who served as general at sea and the Lord Warden of the Cinque Ports from 1656 to 1657. Blake served under Oliver Cromwell during the English Civil War and Anglo-Spanish War, and as the commanding Admiral of the State's Navy during the First Anglo-Dutch War. Blake is recognised as the "chief founder of England's naval supremacy", a dominance subsequently inherited by the British Royal Navy well into the early 20th century. Despite this, due to deliberate attempts to expunge the Parliamentarians from historical records following the Stuart Restoration, Blake's achievements tend to remain relatively unrecognised. Blake's successes, however, are considered to have "never been excelled, not even by Nelson" according to one biographer, while Blake is often compared with Nelson by others.

The Konbaung–Hanthawaddy War (Burmese: ကုန်းဘောင်-ဟံသာဝတီ စစ်) was the war fought between the Konbaung Dynasty and the Restored Hanthawaddy Kingdom of Burma (Myanmar) from 1752 to 1757. The war was the last of several wars between the Burmese-speaking north and the Mon-speaking south that ended the Mon people's centuries-long dominance of the south. The war began in April 1752 as independent resistance movements against Hanthawaddy armies which had just toppled the Toungoo Dynasty. Alaungpaya, who founded the Konbaung Dynasty, quickly emerged as the main resistance leader, and by taking advantage of Hanthawaddy's low troop levels, went on to conquer all of Upper Burma by the end of 1753. Hanthawaddy belatedly launched a full invasion in 1754 but it faltered. The war increasingly turned ethnic in character between the Burman (Bamar) north and the Mon south. Konbaung forces invaded Lower Burma in January 1755, capturing the Irrawaddy Delta and Dagon (Yangon) by May. The French defended port city of Syriam (Thanlyin) held out for another 14 months but eventually fell in July 1756, ending French involvement in the war. The fall of the 16-year-old southern kingdom soon followed in May 1757 when its capital Pegu (Bago) was sacked. Disorganized Mon resistance fell back to the Tenasserim peninsula (present-day Mon State and Tanintharyi Region) in the next few years with Siamese help but was driven out by 1765 when Konbaung armies captured the peninsula from the Siamese. The war proved decisive. Ethnic Burman families from the north began settling in the delta after the war. By the early 19th century, assimilation and intermarriage had reduced the Mon population to a small minority.

Georgia is a country in the Caucasus region on the east coast of the Black Sea. It is located at the intersection of Eastern Europe and West Asia and is generally regarded as part of Europe. It is bordered to the north and northeast by Russia; to the west by the Black Sea, to the south by Turkey and Armenia, and to the southeast by Azerbaijan. It has a population of 3.9 million, of which over a third live in Tbilisi, the capital and largest city. Georgians, who are native to the region and constitute the majority of the population, are ethno-linguistically distinct from their neighboring nations and primarily speak Georgian, a Kartvelian language that has no relation to any other language family in the world.

George Washington (February 22, 1732 [O.S. February 11, 1731] – December 14, 1799) was a Founding Father and the first president of the United States, serving from 1789 to 1797. As commander of the Continental Army, Washington led Patriot forces to victory in the American Revolutionary War against the British Empire. He is commonly known as the Father of His Country for his role in bringing about American independence. Born in the Colony of Virginia, Washington became the commander of the Virginia Regiment during the French and Indian War from 1754 to 1763. He was later elected to the Virginia House of Burgesses, and opposed the oppression of the American colonists by the British Crown. When the American Revolutionary War against the British began in 1775, Washington was appointed commander-in-chief of the Continental Army. He directed a poorly organized and equipped force against disciplined British troops. Washington and his army achieved an early victory at the Siege of Boston in March 1776 but were forced to retreat from New York City in November. Washington crossed the Delaware River and won the battles of Trenton in late 1776 and of Princeton in early 1777, then lost the battles of Brandywine and Germantown later that year. He faced criticism of his command, low troop morale, and a lack of provisions for his forces as the war continued. Ultimately Washington led a combined French and American force to a decisive victory over the British at Yorktown in 1781. In the resulting Treaty of Paris in 1783, the British acknowledged the sovereign independence of the United States. Washington then served as president of the Constitutional Convention in 1787, which drafted the current Constitution of the United States. Washington was unanimously elected the first U.S. president by the Electoral College in 1789 and 1792. He established a strong, well-financed national government while remaining impartial in the fierce rivalry that emerged within his cabinet between Thomas Jefferson and Alexander Hamilton. During the French Revolution, he adopted a policy of neutrality while supporting the Jay Treaty with Britain. Washington set enduring precedents for the office of president, including republicanism, a peaceful transfer of power, the use of the title "Mr. President", and the two-term tradition. His 1796 farewell address became a preeminent statement on republicanism: Washington wrote about the importance of national unity and the dangers that regionalism, partisanship, and foreign influence pose to it. As a planter of tobacco and wheat at Mount Vernon, Washington owned many slaves. He began opposing slavery near the end of his life, and provided in his will for the eventual manumission of his slaves. Washington's image is an icon of American culture and he has been extensively memorialized. His namesakes include the national capital and the State of Washington. In both popular and scholarly polls, he is consistently considered one of the greatest presidents in American history.

Francis II and I (German: Franz II; 12 February 1768 – 2 March 1835) was the last Holy Roman Emperor (as Francis II) from 1792 to 1806, and the first Emperor of Austria (as Francis I) from 1804 to 1835. He was also King of Germany, Hungary, Croatia and Bohemia, and served as the first president of the German Confederation following its establishment in 1815. The eldest son of future Emperor Leopold II and Maria Louisa of Spain, Francis was born in Florence, where his father ruled as Grand Duke of Tuscany. Leopold became Holy Roman Emperor in 1790 but died two years later, and Francis succeeded him. At the time of Francis's accession, his empire was already embroiled in the French Revolutionary Wars, the first of which ended in Austrian defeat and the loss of the left bank of the Rhine to France. After another French victory in the War of the Second Coalition, Napoleon crowned himself Emperor of the French. In response, Francis assumed the title of Emperor of Austria. He continued his leading role as Napoleon's adversary in the Napoleonic Wars, and suffered successive defeats that greatly weakened Austria as a European power. In 1806, after Napoleon created the Confederation of the Rhine, Francis abdicated as Holy Roman Emperor, which in effect marked the dissolution of the Holy Roman Empire. Following the defeat of the Fifth Coalition, Francis ceded more territory to France and was forced to wed his daughter Marie Louise to Napoleon. In 1813, Francis turned against Napoleon and finally defeated him in the War of the Sixth Coalition, forcing the French emperor to abdicate. Austria took part as a leading member of the Holy Alliance at the Congress of Vienna, which was largely dominated by Francis's chancellor Klemens von Metternich, culminating in a new European order and the restoration of most of Francis's ancient dominions. Due to the establishment of the Concert of Europe, which resisted popular nationalist and liberal tendencies, Francis was viewed as a reactionary later in his reign. Francis died in 1835 at the age of 67 and was succeeded by his son, Ferdinand I of Austria.

The Septinsular Republic (Greek: Ἑπτάνησος Πολιτεία, romanized: Heptanēsos Politeia; Italian: Repubblica Settinsulare), also known as the Republic of the Seven United Islands, was an oligarchic republic that existed from 1800 to 1807 under nominal Russian and Ottoman sovereignty in the Ionian Islands (Corfu, Paxoi, Lefkada, Cephalonia, Ithaca, Zakynthos or Zante, and Kythira). The Republic was established after a joint Russo-Ottoman fleet captured the islands and ended a two-year rule by the French Republic. Although the islanders had hoped for complete independence, the new state was granted only autonomy, becoming tributary to the Ottoman Porte, and de facto under Russian domination. Nevertheless, it was the first time that Greeks had been granted self-government since the fall of the last remnants of the Byzantine Empire to the Ottomans in the mid-15th century. In 1807, the republic was ceded to Napoleon's French Empire, but the islands kept their institutions of government. The British gradually took control of the islands from 1809 on, and following the Treaty of Paris, the islands were formally organised into the United States of the Ionian Islands under British protection.

The French Empire, known retroactively as the First French Empire, and colloquially as Napoleonic France, was the empire ruled by Napoleon Bonaparte, who established French hegemony over much of continental Europe at the beginning of the 19th century. It lasted from 18 May 1804 to 6 April 1814 and again briefly from 20 March 1815 to 7 July 1815, when Napoleon was exiled to Saint Helena.

Auguste René Caillié (French pronunciation: [ʁəne kaje]; 19 November 1799 – 17 May 1838) was a French explorer and the first European to return alive from the town of Timbuktu. Caillié had been preceded at Timbuktu by a British officer, Major Gordon Laing, who was murdered in September 1826 on leaving the city. Caillié was therefore the first to return alive. Caillié was born in western France in a village near the port of Rochefort. His parents were poor and died while he was still young. At the age of 16 he left home and signed up as a member of the crew on a French naval vessel sailing to Saint-Louis on the coast of modern Senegal in western Africa. He stayed there for several months and then crossed the Atlantic to Guadeloupe on a merchantman. He made a second visit to West Africa two years later when he accompanied a British expedition across the Ferlo Desert to Bakel on the Senegal River. Caillié returned to Saint-Louis in 1824 with a strong desire to become an explorer and visit Timbuktu. In order to avoid some of the difficulties experienced by the earlier expeditions, he planned to travel alone disguised as a Muslim. He persuaded the French governor in Saint-Louis to help finance a stay of 8 months with the nomadic people in the Brakna Region of southern Mauritania where he learned Arabic and the customs of Islam. He failed to obtain further funding from either the French or the British governments, but encouraged by the prize of 9,000 francs offered by the Société de Géographie in Paris for the first person to return with a description of Timbuktu, he decided to fund the journey himself. He worked for a few months in the British colony of Sierra Leone to save some money, then travelled by ship to Boké on the Rio Nuñez in modern Guinea. From there in April 1827 he set off across West Africa. He arrived in Timbuktu a year later and stayed there for two weeks before heading across the Sahara Desert to Tangier in Morocco. On his return to France, he was awarded the prize of 9,000 francs by the Société de Géographie and, helped by the scholar Edme-François Jomard, published an account of his journey. In 1830, he was awarded the Gold Medal by the Société de Géographie. Caillié married and settled near his birthplace. He suffered from poor health and died of tuberculosis aged 38.

The United States Congress is the legislative branch of the federal government of the United States. It is a bicameral legislature, including a lower body, the U.S. House of Representatives, and an upper body, the U.S. Senate. They both meet in the United States Capitol in Washington, D.C.

The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States between the Union ("the North") and the Confederacy ("the South"), which was formed in 1861 by states that had seceded from the Union to preserve slavery in the United States. The South saw slavery as threatened because of the election of Abraham Lincoln and the growing abolitionist movement in the North. The war ended with Union victory, the dissolution of the Confederacy and the abolition of slavery, freeing four million African Americans. Decades of controversy over slavery came to a head when Abraham Lincoln, a Republican who opposed slavery's expansion, won the 1860 presidential election. Seven slave states in the South responded to Lincoln's victory by seceding from the United States and forming the Confederate States of America. The Confederacy seized US forts and other federal assets in the South. The war began on April 12, 1861, when the Confederacy bombarded Fort Sumter in South Carolina. A wave of enthusiasm for war swept over the North and South, as military recruitment soared. Four more Southern states seceded after the war began and, led by its president, Jefferson Davis, the Confederacy comprised eleven states, containing a third of the US population. Four years of intense combat, mostly in the South, ensued. During 1861–1862 in the western theater, the Union made permanent gains, though in the eastern theater the conflict was inconclusive. The abolition of slavery became a Union war goal on January 1, 1863, when Lincoln issued the Emancipation Proclamation, which declared all slaves in rebel states to be free, applying to more than 3.5 million of the 4 million enslaved people in the country. To the west, the Union first destroyed the Confederacy's river navy by the summer of 1862, then much of its western armies, and seized New Orleans. The successful 1863 Union siege of Vicksburg split the Confederacy in two at the Mississippi River, while Confederate general Robert E. Lee's incursion north failed at the Battle of Gettysburg. General Ulysses S. Grant's western successes led Lincoln to promote him to command of all Union armies in 1864. Inflicting an ever-tightening naval blockade of Confederate ports, the Union marshaled resources and manpower to attack the Confederacy from all directions. This led to the fall of Atlanta in 1864 to Union general William Tecumseh Sherman, followed by his March to the Sea, which culminated in his taking Savannah. The last significant battles raged around the ten-month siege of Petersburg, gateway to the Confederate capital of Richmond. The Confederates abandoned Richmond, and on April 9, 1865, Lee surrendered to Grant following the Battle of Appomattox Court House, setting in motion the end of the war. Lincoln lived to see this victory but was shot by an assassin on April 14, dying the next day. By the end of the war, much of the South's infrastructure had been destroyed. The Confederacy collapsed, the Thirteenth Amendment abolished slavery, and four million enslaved black people were freed. The war-torn nation then entered the Reconstruction era in an attempt to rebuild the country, bring the former Confederate states back into the United States, and grant civil rights to freed slaves. The war is one of the most extensively studied and written about episodes in the history of the United States. It remains the subject of cultural and historiographical debate. Of continuing interest is the myth of the Lost Cause of the Confederacy. The war was among the first to use industrial warfare. Railroads, the electrical telegraph, steamships, the ironclad warship, and mass-produced weapons were widely used. The war left an estimated 700,000 soldiers dead, along with an undetermined number of civilian deaths, making it the deadliest in American history. The technology and brutality of the Civil War foreshadowed the coming world wars.

Thaddeus Sobieski Constantine Lowe, also known as Professor T. S. C. Lowe, was an American Civil War aeronaut, scientist and inventor, mostly self-educated in the fields of chemistry, meteorology, and aeronautics, and the father of military aerial reconnaissance in the United States. By the late 1850s he was well known for his advanced theories in the meteorological sciences as well as his balloon building. Among his aspirations were plans for a transatlantic flight.

Louis Pasteur was a French chemist, pharmacist, and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation, and pasteurization, the last of which was named after him. His research in chemistry led to remarkable breakthroughs in the understanding of the causes and prevention of diseases, which laid down the foundations of hygiene, public health and much of modern medicine. Pasteur's works are credited with saving millions of lives through the development of vaccines for rabies and anthrax. He is regarded as one of the founders of modern bacteriology and has been honored as the "father of bacteriology" and the "father of microbiology".

Angelo Secchi (Italian pronunciation: [ˈandʒelo ˈsekki]; 28 June 1818 – 26 February 1878) was an Italian Catholic priest and astronomer from the Italian region of Emilia. He was director of the observatory at the Pontifical Gregorian University (then called the Roman College) for 28 years. He was a pioneer in astronomical spectroscopy, and was one of the first scientists to state authoritatively that the Sun is a star.

The April Uprising (Bulgarian: Априлско въстание, romanized: Aprilsko vastanie) was an insurrection organised by the Bulgarians in the Ottoman Empire from April to May 1876. The rebellion was suppressed by irregular Ottoman bashi-bazouk units that engaged in indiscriminate slaughter of both rebels and non-combatants (see Batak massacre). The American community around Robert College in Istanbul, the Protestant mission in Plovdiv headed by J.F. Clarke as well as two other Americans, journalist Januarius MacGahan and diplomat Eugene Schuyler, were indispensable in bringing knowledge of Ottoman atrocities to the wider European public. Their reports of the events, which came to be known in the press as the Bulgarian Horrors and the Crime of the Century, caused a public outcry across Europe and mobilised both common folks and famous intellectuals to demand a reform of the failed Ottoman model of governance of the Bulgarian lands. The shift in public opinion, in particular, in the Ottoman Empire's hitherto closest ally, the British Empire, eventually led to the re-establishment of a separate Bulgarian state in 1878.

Humanum genus is a papal encyclical promulgated on 20 April 1884 by Pope Leo XIII. Released in the ascent of the industrial age, Marxism, and the aftermath of the September 20, 1870, Capture of Rome by the Kingdom of Italy military forces from the Papal States, Humanum genus is principally a condemnation of Freemasonry. It states that the late 19th century was a dangerous era for the Roman Catholic Church, largely due to numerous concepts and practices it attributes to Freemasonry, namely naturalism, popular sovereignty, and the separation of church and state. Some of the strictures found in Humanum genus still remain in force today.

Pierre Curie was a French physicist and chemist, and a pioneer in crystallography and magnetism. He shared one half of the 1903 Nobel Prize in Physics with his wife, Maria Skłodowska-Curie, for their work on radioactivity. With their win, the Curies became the first married couple to win a Nobel Prize, launching the Curie family legacy of five Nobel Prizes.

The New South Wales Rugby League Ltd (NSWRL) is an Australian rugby league football competition operator in New South Wales and the Australian Capital Territory and is a member of the Australian Rugby League Commission.

The Ludlow Massacre was a mass killing perpetrated by anti-striker militia during the Colorado Coalfield War. Soldiers from the Colorado National Guard and private guards employed by Colorado Fuel and Iron Company (CF&I) attacked a tent colony of roughly 1,200 striking coal miners and their families in Ludlow, Colorado, on April 20, 1914. Approximately 21 people were killed, primarily miners' wives and children. John D. Rockefeller Jr. was a part-owner of CF&I who had recently appeared before a United States congressional hearing on the strikes, and he was widely blamed for having orchestrated the massacre. The massacre was the seminal event of the 1913–1914 Colorado Coalfield War, which began with a general United Mine Workers of America strike against poor labor conditions in CF&I's southern Colorado coal mines. The strike was organized by miners working for the Rocky Mountain Fuel Company and Victor-American Fuel Company. Ludlow was the deadliest single incident during the Colorado Coalfield War and spurred a ten-day period of heightened violence throughout Colorado. In retaliation for the massacre at Ludlow, bands of armed miners attacked dozens of anti-union establishments, destroying property and engaging in several skirmishes with the Colorado National Guard along a 225-mile (362 km) front from Trinidad to Louisville. From the strike's beginning in September 1913 to intervention by federal soldiers under President Woodrow Wilson's orders on April 29, 1914, an estimated 69 to 199 people were killed. Historian Thomas G. Andrews declared it the "deadliest strike in the history of the United States." The Ludlow Massacre was a watershed moment in American labor relations. Historian and author Howard Zinn described it as "the culminating act of perhaps the most violent struggle between corporate power and laboring men in American history". Congress responded to public outrage by directing the House Committee on Mines and Mining to investigate the events. Its report, published in 1915, was influential in promoting child labor laws and an eight-hour work day. The Ludlow townsite and the adjacent location of the tent colony, 18 miles (29 km) northwest of Trinidad, Colorado, is now a ghost town. The massacre site is owned by the United Mine Workers of America, which erected a granite monument in memory of those who died that day. The Ludlow tent colony site was designated a National Historic Landmark on January 16, 2009, and dedicated on June 28, 2009. Subsequent investigations immediately following the massacre and modern archeological efforts largely support some of the strikers' accounts of the event.

World War I, or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. One of the deadliest conflicts in history, World War I resulted in an estimated 15 to 22 million deaths, including those in war crimes and genocides. The war also helped spread the Spanish flu pandemic. The conflict saw important developments in weaponry, including the first large-scale use of machine guns, artillery, aircraft, chemical weapons, and tanks.

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a transcontinental country that spanned much of Eurasia from its formation in 1922 until its dissolution in 1991. It was the world's third-most populous country, the largest by area, and bordered twelve other countries. A diverse multinational state, it was organized as a federal union of national republics, with the largest and most populous being the Russian Soviet Federative Socialist Republic (SFSR). The world's flagship communist state, it was governed by the Communist Party under Marxism–Leninism, through soviet councils. The Soviet economy was also centrally planned. Its capital and largest city was Moscow.

World War II, or the Second World War, was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many engaging in total war on an unprecedented scale. World War II was the deadliest conflict in history, causing the deaths of 60 to 75 million people, a majority of whom were civilians. Millions died as a result of massacres, starvation, disease, and genocides including the Holocaust. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

The Führerbunker was an air-raid shelter built and located near the Reich Chancellery in Berlin, Germany. It was part of a subterranean bunker-complex constructed in two phases in 1936 and 1944, and became the last of the Führer Headquarters used by Adolf Hitler during World War II.

Nazi Germany conducted medical experiments on prisoners in its concentration camps mainly between 1942 and 1945. There were 15,754 documented victims, of various nationalities and ages, although the true number is believed to be more. About a quarter of documented victims were killed and survivors generally experienced severe permanent injuries. At Auschwitz and other camps, under the direction of Eduard Wirths, selected inmates were subjected to various experiments that were designed to help German military personnel in combat situations, develop new weapons, aid in the recovery of military personnel who had been injured, and to advance Nazi racial ideology and eugenics, including the twin experiments of Josef Mengele. Aribert Heim conducted similar medical experiments at Mauthausen. After the war, these crimes were tried at what became known as the Doctors' Trial, and revulsion at the abuses led to the development of the Nuremberg Code of medical ethics. Some Nazi physicians in the Doctors' Trial argued that military necessity justified their experiments, or compared their victims to collateral damage from Allied bombings.

The League of Nations (LN or LoN; French: Société des Nations [sɔsjete de nɑsjɔ̃], SdN) was the first worldwide intergovernmental organisation whose principal mission was to maintain world peace. It was founded on 10 January 1920 by the Paris Peace Conference that ended the First World War. The main organisation ceased operations on 18 April 1946 when many of its components were relocated into the new United Nations (UN) which was created in the aftermath of the Second World War. The League of Nations was the precursor organisation to the United Nations. The League's primary goals were stated in its eponymous Covenant. They included preventing wars through collective security and disarmament and settling international disputes through negotiation and arbitration. Its other concerns included labour conditions, just treatment of native inhabitants, human and drug trafficking, the arms trade, global health, prisoners of war, and protection of minorities in Europe. The Covenant of the League of Nations was signed on 28 June 1919 as Part I of the Treaty of Versailles, and it became effective with the rest of the Treaty on 10 January 1920. Australia was granted the right to participate as an autonomous member nation, marking the start of Australian independence on the global stage. The first meeting of the Council of the League took place on 16 January 1920, and the first meeting of the Assembly of the League took place on 15 November 1920. In 1919, U.S. president Woodrow Wilson won the Nobel Peace Prize for his role as the leading architect of the League. Despite this, he was ultimately unsuccessful in getting his country to join it. The diplomatic philosophy behind the League represented a fundamental shift from the preceding hundred years. The League lacked its own armed force and depended on the victorious Allied Powers of World War I (Britain, France, Italy and Japan were the initial permanent members of the Council) to enforce its resolutions, keep to its economic sanctions, or provide an army when needed. The great powers were often reluctant to do so. Sanctions could hurt League members, so they were reluctant to comply with them. During the Second Italo-Ethiopian War, when the League accused Italian soldiers of targeting International Red Cross and Red Crescent Movement medical tents, Benito Mussolini responded that "the League is very well when sparrows shout, but no good at all when eagles fall out." At its greatest extent from 28 September 1934 to 23 February 1935, it had 58 members. After some notable successes and some early failures in the 1920s, the League ultimately proved incapable of preventing aggression by the Axis powers in the 1930s. Its credibility was weakened because the United States never joined. Japan and Germany left in 1933, Italy left in 1937, and Spain left in 1939. The Soviet Union only joined in 1934 and was expelled in 1939 after invading Finland, but not after invading Poland earlier [17 September 1939- see Ribbentrop-Molotov Pact] Furthermore, the League demonstrated an irresolute approach to sanction enforcement for fear it might only spark further conflict, further decreasing its credibility. The onset of the Second World War in 1939 showed that the League had failed its primary purpose: to prevent another world war. It was largely inactive until its abolition. The League lasted for 26 years; the United Nations effectively replaced it in 1945, inheriting several agencies and organisations founded by the League, with the League itself formally dissolving the following year. Current scholarly consensus views that, even though the League failed to achieve its main goal of world peace, it did manage to build new roads towards expanding the rule of law across the globe; strengthened the concept of collective security, gave a voice to smaller nations; fostered economic stabilisation and financial stability, especially in Central Europe in the 1920s; helped to raise awareness of problems such as epidemics, slavery, child labour, colonial tyranny, refugee crises and general working conditions through its numerous commissions and committees; and paved the way for new forms of statehood, as the mandate system put the colonial powers under international observation.

The Amethyst incident, also known as the Yangtze incident, was a historic event that occurred on the Yangtze River for three months in the summer of 1949, during the late phase of the Chinese Civil War. The incident involved the Communist People's Liberation Army (PLA), who were in the process of a river-crossing offensive to overthrow the Nationalist Government, and four British Royal Navy ships HMS Amethyst, HMS Black Swan, HMS Consort and HMS London. The British warships, whose claimed right of passage along the Yangtze had been unchallenged previously since the 1858 Treaty of Tientsin with the late Qing dynasty, came under bombardment by PLA artillery and were forced to withdraw permanently from Chinese territorial waters.

The Cold War was a period of international geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc. It began in the aftermath of the Second World War and ended with the dissolution of the Soviet Union in 1991. The term cold war is used because there was no direct fighting between the two superpowers, though each supported opposing sides in regional conflicts known as proxy wars. In addition to the struggle for ideological and economic influence and an arms race in both conventional and nuclear weapons, the Cold War was expressed through technological rivalries such as the Space Race, espionage, propaganda campaigns, embargoes, and sports diplomacy.

John Enoch Powell was a British politician, scholar, soldier and writer. He was the Member of Parliament (MP) for Wolverhampton South West for the Conservative Party from 1950 to February 1974 and the MP for South Down for the Ulster Unionist Party (UUP) from October 1974 to 1987. He was Minister of Health from 1960 to 1963 in the second Macmillan ministry and was Shadow Secretary of State for Defence from 1965 to 1968 in the Shadow Cabinet of Edward Heath.

South African Airways Flight 228 was a scheduled flight from Johannesburg, South Africa, to London, England. The Boeing 707 operating the flight, which was only six weeks old, flew into the ground soon after take-off after a scheduled stopover in Windhoek, South West Africa on 20 April 1968. Five passengers survived, while 123 people died. The subsequent investigation determined that the accident was attributable largely to pilot error; the manufacturer subsequently also recognised the lack of a ground proximity warning system in its aircraft. The accident is the deadliest aviation accident to date in Namibia.

The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which landed the first humans on the Moon in 1969. The Apollo program was conceived in 1960 in the Dwight D. Eisenhower presidency during Project Mercury and executed after Project Gemini. The Apollo program was later dedicated to President John F. Kennedy's national goal, "before this decade is out, of landing a man on the Moon and returning him safely to the Earth" in his address to the U.S. Congress on May 25, 1961.

In 1985, a raid took place at a laboratory belonging to the University of California, Riverside (UCR) that resulted in the removal of a monkey by the Animal Liberation Front (ALF). This monkey, called Britches, was a stump-tailed macaque who was born into a breeding colony at UCR. He was removed from his mother at birth, had his eyelids sewn shut, and had an electronic sonar device attached to his head—a Trisensor Aid, an experimental version of a blind travel aid, the Sonicguide—as part of a three-year sensory-deprivation study involving 24 infant monkeys. The experiments were designed to study the behavioral and neural development of monkeys reared with a sensory substitution device.

Air France Flight 422 was a scheduled flight on 20 April 1998 by Air France from Bogotá, Colombia, to Quito, Ecuador, covering the final leg of a flight from Paris to Quito. The Boeing 727 was destroyed, killing all 53 people on board, when it crashed into the Eastern Hills of Bogotá because of foggy weather and low visibility after taking off from Bogotá's El Dorado International Airport. The plane was owned by TAME, the Ecuadorian airline, but was being operated on a wet-lease basis to Air France as the final leg of its flight from Paris.

On April 20, 1999, high school senior students Eric Harris and Dylan Klebold shot and killed 13 students and one teacher in a school shooting and attempted bombing at Columbine High School in Columbine, Colorado, United States. Twenty people were injured by the gunfire, and three others were injured while trying to escape. The attack ended when Harris and Klebold committed suicide. The Columbine massacre was the deadliest mass shooting at a K–12 school in U.S. history until the Sandy Hook Elementary School shooting in December 2012. It was also the deadliest high school shooting until Parkland high school in 2018. Columbine is considered among the most infamous massacres in the United States, which as of June 2025, had inspired more than 70 copycat crimes, a phenomenon dubbed the Columbine effect, and Columbine has become a byword for modern school shootings.

Nicoll Highway is a major arterial road in Singapore which links the junctions of Guillemard Road, Sims Way and Mountbatten Road in Kallang to the junctions of Esplanade Drive, Raffles Avenue and Stamford Road in the city. En route, it passes through the areas of Kallang, Kampong Glam and Marina Centre.

The Johnson Space Center shooting was an incident of hostage taking that occurred on April 20, 2007, in Building 44, the Communication and Tracking Development Laboratory, at the Lyndon B. Johnson Space Center (JSC) in Houston, Texas, United States. The gunman, William Phillips, an employee for Jacobs Engineering who worked at Building 44, shot and killed one person and took a hostage for over three hours before committing suicide. Police said Phillips was under review for poor job performance and he feared being dismissed.

Danica Sue Patrick is an American former professional racing driver who competed in the IndyCar Series from 2005 to 2011 and the NASCAR Cup Series from 2012 to 2018. She is the most successful woman in the history of American open-wheel car racing—her victory in the 2008 Indy Japan 300 is the only win by a woman in IndyCar.

Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible offshore drilling rig owned by Transocean and operated by the BP company. On 20 April 2010, while drilling in the Gulf of Mexico at the Macondo Prospect, a blowout caused an explosion on the rig that killed 11 people and ignited a fireball visible from 40 miles (64 km) away. The fire was inextinguishable and, two days later, on 22 April, the Horizon collapsed, leaving the well gushing at the seabed and becoming the largest marine oil spill in history.

Bhoja Air Flight 213 was a domestic scheduled passenger flight operated by Pakistani private airline Bhoja Air from Karachi to Islamabad. On 20 April 2012, the Boeing 737-200 aircraft serving the route crashed in bad weather during the final approach, killing all 121 passengers and 6 crew on board. It remains the second deadliest air disaster in Pakistan, after the 2010 crash of Airblue Flight 202.

The Garowe attack was a bombing of a UN van in Garowe, Puntland, Somalia. Between 7 and 10 people were killed, including the attacker and four UNICEF workers. The Al-Shabaab militant group claimed responsibility for the blast. The Puntland administration subsequently appointed a governmental committee to probe the circumstances surrounding the attack, and apprehended over a dozen suspects.

The price of oil, or the oil price, generally refers to the spot price of a barrel of benchmark crude oil—a reference price for buyers and sellers of crude oil such as West Texas Intermediate (WTI), Brent Crude, Dubai Crude, OPEC Reference Basket, Tapis crude, Bonny Light, Urals oil, Isthmus, and Western Canadian Select (WCS) among others. Oil prices are determined by global supply and demand, rather than any country's domestic production level, although the Organization of the Petroleum Exporting Countries (OPEC) cartel increases oil prices.

Starship is a two-stage, fully reusable, super heavy-lift launch vehicle under development by American aerospace company SpaceX. Currently built and launched from Starbase in Texas, it is intended as the successor to the company's Falcon 9 and Falcon Heavy rockets, and is part of SpaceX's broader reusable launch system development program. If completed as designed, Starship would be the first fully reusable orbital rocket and have the highest payload capacity of any launch vehicle to date. As of September 28, 2026, Starship has launched 14 times, with 9 successful flights and 5 failures.