April 21 in History

Romulus (, Classical Latin: [ˈroːmʊɫʊs]) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of these traditions incorporate elements of folklore, and it is not clear to what extent a historical figure underlies the mythical Romulus, the events and institutions ascribed to him were central to the myths surrounding Rome's origins and cultural traditions.

The Battle of Mutina took place on 21 April 43 BC between the forces loyal to the Senate under consuls Gaius Vibius Pansa and Aulus Hirtius, supported by the forces of Caesar Octavian, versus the forces of Mark Antony which were besieging the troops of Decimus Brutus. The latter, one of Caesar's assassins, held the city of Mutina (present-day Modena) in Cisalpine Gaul. Six days earlier, the Battle of Forum Gallorum had ended with heavy losses on both sides and the mortal wounding of consul Pansa. Hirtius and Octavian then launched an attack on Antony's camp, seeking to break the siege. Amid bloody fighting, Hirtius was killed, leaving the army and republic leaderless. Octavian saw action in the battle, recovered Hirtius' body, and managed to avoid defeat. Decimus Brutus also participated in the fighting with part of his forces locked up in the city. Command of Hirtius' legions then devolved to Caesar Octavian. Decimus Brutus, marginalized after the battle, soon fled Italy in the hopes of joining fellow assassins Marcus Junius Brutus and Gaius Cassius Longinus; he was, however, captured and executed en route. After the battle, Mark Antony decided to give up the siege and retreated westward along the via Aemilia, escaping the enemy forces and rejoining the reinforcements of his lieutenant Publius Ventidius Bassus. The battle brought the brief War of Mutina to a victorious end for the Republicans allied with Caesar Octavian, but the situation would change completely the following autumn with the formation of the Second Triumvirate of Antony, Octavian, and Lepidus.

The Laguna Copperplate Inscription is an official acquittance (debt relief) certificate inscribed onto a copper plate in the Shaka year 822 (Gregorian A.D. 900). It is the earliest-known, extant, calendar-dated document found within the Philippines. The plate was found in 1987 by a laborer near the mouth of the Lumbang River in Wawa, Lumban, Laguna, in the Philippines. The inscription was mainly written in Old Malay using the Old Javanese script called Kawi script, with several technical Sanskrit words and either Old Javanese or Old Tagalog honorifics. After it was found, the text was first translated in 1991 by Antoon Postma, a Dutch anthropologist and Hanunó'o script researcher. The inscription documents the existence and names of several surrounding states as of A.D. 900, such as the Tagalog city-state of Tondo. Some historians associate the toponym Medang in this inscription regarding the Medang palace in Java at that time, although the name is a common term of Malayo-Polynesian origin.

The Archdiocese of Pisa (Latin: Archidioecesis Pisana) is a Latin Church metropolitan see of the Catholic Church in Pisa, Italy. It was founded in the 4th century and elevated to the dignity of an archdiocese on 21 April 1092 by Pope Urban II. The seat of the bishop is the cathedral of the Assumption in the Piazza del Duomo. The archbishop of Pisa presides over the Ecclesiastical Province of Pisa, which includes the dioceses of Livorno, Massa Carrara-Pontremoli, Pescia, and Volterra. In 2025, Pope Francis nominated Fr. Saverio Cannistrà, OCD, former superior general of the Order of Discalced Carmelites as archbishop of Pisa, replacing Giovanni Paolo Benotto, who has been archbishop since 2008.

On 19 April 1506, a crowd of churchgoers in Lisbon attacked and killed several people in the congregation whom they suspected were Jews. The violence escalated into a city-wide, antisemitic riot that killed between 500 and 4,000 "New Christians" (Cristãos-Novos), the name for Jews who had been forcibly converted to Christianity.

Henry VIII (28 June 1491 – 28 January 1547) was King of England and Ireland from 22 April 1509 until his death in 1547. Henry was born in Greenwich as the second son of Henry VII and Elizabeth of York. His elder brother, Arthur, Prince of Wales, was heir apparent and married Catherine of Aragon, a Spanish princess. Arthur died in 1502, and Henry was created Prince of Wales in 1504. He acceded to the throne upon his father's death in 1509, marrying Catherine with a papal dispensation. He was described as an attractive, educated, and accomplished king during the early years of his reign. Henry grew dissatisfied with the marriage to Catherine, appealing to Pope Clement VII for an annulment. Clement refused, and Archbishop of Canterbury Thomas Cranmer declared the marriage void in the eyes of the Church of England in 1533. Clement objected to Cranmer's verdict and excommunicated Henry from the Catholic Church. Henry then passed the Acts of Supremacy, establishing himself as Supreme Head of the Church of England and thereby relieving his realms from obedience to the pope. He dissolved Catholic monasteries and seized their wealth, contributing to the English Reformation. Considered one of the greatest monarchs in English history, Henry grew more tyrannical, egotistical, lustful, and paranoid by the end of his life. He is known for his six marriages, and especially his long effort to annul his marriage to Catherine of Aragon so that he could remarry in pursuit of a male heir. He ordered the beheadings of two of his wives, Anne Boleyn and Catherine Howard. In his later years, Henry was morbidly obese and immobile, with a gangrenous leg wound contracted from a jousting accident in 1536. He was also said to have suffered from diabetes, oedema, and organ failure. He was buried at St George's Chapel in Windsor Castle and was succeeded by his only surviving son, Edward VI.

The Lodi dynasty was a royal family that ruled the Sultanate of Delhi from 1451 to 1526. It was the fifth and final dynasty of the Delhi Sultanate, and was founded by Bahlul Lodi when he replaced the Sayyid dynasty.

The Wignacourt Aqueduct (Maltese: L-Akwedott ta' Wignacourt) is a 17th-century aqueduct in Malta, which was built by the Order of Saint John to carry water from springs in Dingli and Rabat to the newly built capital city Valletta. The aqueduct carried water through underground pipes and over arched viaducts across depressions in the ground. The first attempts to build the aqueduct were made by Grand Master Martin Garzez in 1596, but construction was suspended before being continued in 1610. The watercourse was inaugurated five years later on 21 April 1615. Several engineers took part in the project, including Bontadino de Bontadini, Giovanni Attard and Natale Tomasucci. The aqueduct was named after Grand Master Alof de Wignacourt, who partially financed its construction. The aqueduct remained in use until the 20th century. Most of its arches still survive today, and can still be seen in the localities of Attard, Balzan, Birkirkara, Fleur-de-Lys and Santa Venera. Other remains of the aqueduct include water towers at Santa Venera, Hamrun and Floriana, and several fountains in Floriana and Valletta.

Bangkok, known in Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and largest city of Thailand. The city occupies 1,568.7 square kilometres (605.7 sq mi) in the Chao Phraya River delta in central Thailand and has an estimated population of 9.1 million people as of 2024, 15.9% of the country's population. Over 17.4 million people live within the surrounding Bangkok Metropolitan Region as of the 2021 estimate, making Bangkok a megacity and an extreme primate city, dwarfing Thailand's other urban centres in both size and importance to the national economy.

John Adams (October 30, 1735 – July 4, 1826) was a Founding Father and the second president of the United States from 1797 to 1801. Before his presidency, he was a leader of the American Revolution that achieved independence from Great Britain. During the latter part of the Revolutionary War and in the early years of the new nation, he served the Continental Congress of the United States as a senior diplomat in Europe. Adams was the first vice president of the United States, serving from 1789 to 1797. He was a dedicated diarist and regularly corresponded with contemporaries, including his wife and advisor Abigail Adams and his friend and rival Thomas Jefferson. A lawyer and political activist prior to the Revolution, Adams was devoted to the right to counsel and presumption of innocence. He defied anti-British sentiment and successfully defended British soldiers against murder charges arising from the Boston Massacre. Adams was a Massachusetts delegate to the Continental Congress and became a leader of the revolution. He assisted Jefferson in drafting the Declaration of Independence in 1776 and was its primary advocate in Congress. As a diplomat, he represented the United States in France and the Netherlands during the war. He helped negotiate the peace treaty with Great Britain, secured Dutch loans for the American government, and was the first United States ambassador to Great Britain. Adams was the primary author of the Massachusetts Constitution in 1780, which, with his other political writings, influenced the United States Constitution. Adams was elected to two terms as vice president under President George Washington and was elected as the United States' second president in 1796 under the banner of the Federalist Party. Adams's term was dominated by the issue of the French Revolutionary Wars, and his insistence on American neutrality led to fierce criticism from both the Jeffersonian Republicans and from some in his own party, led by his rival Alexander Hamilton. Adams signed the controversial Alien and Sedition Acts and built up the Army and Navy in an undeclared naval war with France. He was the first president to reside in the White House. In his 1800 bid for reelection to the presidency, opposition from Federalists and accusations of despotism from Jeffersonians led to Adams losing to his vice president and former friend, Thomas Jefferson. After his defeat, he retired to Massachusetts. He eventually resumed his friendship with Jefferson by initiating a continuing correspondence. John Adams died on July 4, 1826 – the fiftieth anniversary of the adoption of the Declaration of Independence. The Adams political family included his son John Quincy Adams, the sixth president. Adams and his son are the only presidents of the first twelve who never owned slaves. Most historians have favorably ranked his administration.

George Washington's reception at Trenton was a celebration hosted by the Ladies of Trenton social club on April 21, 1789, in Trenton, New Jersey, as George Washington, then president-elect, journeyed from his home at Mount Vernon to his first inauguration in the then capital of the United States, New York City. A ceremonial triumphal arch was erected on the bridge over the Assunpink Creek to commemorate his two victories here, the Battle of Trenton on December 26, 1776 and the Battle of the Assunpink Creek on January 2, 1777.

Joaquim José da Silva Xavier (Portuguese pronunciation: [ʒoa'kĩ ʒo'zɛ da 'siwvɐ ʃavi'ɛɾ]; 12 November 1746 – 21 April 1792), known as Tiradentes (pronounced [tʃiɾɐˈdẽtʃis]), was a leading member of the colonial Brazilian revolutionary movement known as the Inconfidência Mineira, whose aim was full independence from Portuguese rule and the creation of a republic. When the conspirators plot was uncovered by authorities, Tiradentes was arrested, tried and publicly hanged. Since the advent of the Brazilian Republic, Tiradentes has been considered a national hero of Brazil and patron of the Military Police.

The War of the First Coalition was a set of wars between a coalition of several European powers and France fought from 1792 to 1797. The coalition was only loosely allied and fought without much coordination; each power wanted to annex a different part of France should they defeat the French, something that never occurred.

The Wahhabi sack of Karbala (Arabic: الهجوم الوهابي على كربلاء) occurred on 21 April 1802, under the rule of Abdulaziz bin Muhammad Al Saud, the second ruler of the Emirate of Diriyah, where approximately 12,000 Wahhabis from Najd attacked the Shia city of Karbala in Ottoman Iraq. The raid was conducted in retaliation against attacks on Hajj caravans by Iraqi tribes and coincided with the anniversary of Ghadir Khumm. The Wahhabis killed between 2,000and 5,000 of the inhabitants and plundered the tomb of Husayn ibn Ali, grandson of the Islamic prophet Muhammad and son of Ali ibn Abi Talib, and destroyed its dome, seizing a large quantity of spoils, including gold, Persian carpets, money, pearls, and guns that had accumulated in the tomb, most of them donations. The attack lasted for eight hours, after which the Wahhabis left the city with more than 4,000 camels carrying their plunder.

The action of 21 April 1806 was a minor engagement between the French and British navies off the Cape Colony during the Napoleonic Wars. The Isle Bonaparte and Isle de France were two French colonies in the Indian Ocean, from which privateers and frigate squadrons could engage in commerce raiding and disrupt British shipping. After encountering a strongly escorted British convoy, the 40-gun Cannonière attempted to flee, but was rejoined by the 74-gun HMS Tremendous. In the ensuing battle, Captain Bourayne displayed superior sailmanship and managed to fend off his much stronger opponent by a combination of manoeuvers that rendered the batteries of Tremendous ineffective, and threatened her with sustaining raking fire. The French frigate thus managed to evade and escape.

Landshut is a town in Bavaria, Germany, on the banks of the River Isar. Landshut is the capital of Lower Bavaria, one of the seven administrative regions of the Free State of Bavaria, and the seat of the surrounding district. With a population of more than 75,000, Landshut is the largest city in Lower Bavaria.

The Texas Revolution (October 2, 1835 – April 21, 1836) was a rebellion by Anglo-American immigrants as well as Hispanic Texans (known as Texians and Tejanos respectively) against the centralist government of Mexico in the Mexican state of Coahuila y Tejas. Although the uprising was part of a larger revolt that included other provinces opposed to the regime of President Miguel Barragán and General Antonio López de Santa Anna, the Mexican government believed the United States had instigated the Texas insurrection with the goal of annexation. The Mexican Congress passed the Tornel Decree, declaring that any foreigners fighting against Mexican troops "will be deemed pirates and dealt with as such, being citizens of no nation presently at war with the Republic and fighting under no recognized flag". Only the province of Texas succeeded in breaking with Mexico, establishing the Republic of Texas. It was eventually annexed by the United States about a decade later. The revolution began in October 1835, after a decade of political and cultural clashes between the Mexican government and the large and growing population of Anglo-American settlers in Texas. The Mexican government had become increasingly centralized, stripping Texas of its autonomy. The rights of its citizens had become further curtailed in turn, particularly regarding immigration from the United States, and the holding of slaves as property. Mexico had officially abolished slavery in 1829, but had made an exemption for Texas, however this exemption was not constitutionalized, which made many slave owners in Texas still feel unsatisfied. Although slavery is not mentioned explicitly in the Texas Declaration of Independence, the ownership of human beings in bondage as property was of great importance to many of the settlers. Texians and Tejanos disagreed on whether the ultimate goal was independence or a return to the Mexican Constitution of 1824. While delegates at the Consultation (provisional government) debated the war's motives, Texians and a flood of volunteers from the United States defeated the small garrisons of Mexican soldiers by mid-December 1835. The Consultation declined to declare independence and installed an interim government, whose infighting led to political paralysis and a dearth of effective governance in Texas. An ill-conceived proposal to invade Matamoros siphoned much-needed volunteers and provisions from the fledgling Texian Army. In March 1836, a second political convention declared independence and appointed leadership for the new Republic of Texas. Determined to avenge Mexico's honor, Santa Anna vowed to personally retake Texas. His Army of Operations entered Texas in mid-February 1836 and found the Texians completely unprepared. Mexican general José de Urrea led a contingent of troops on the Goliad Campaign up the Texas coast, defeating all Texian troops in his path and executing most of those who surrendered. Santa Anna led a larger force to San Antonio de Béxar (or Béxar), where his troops defeated the Texian garrison in the Battle of the Alamo, killing almost all of the defenders. A newly created Texian army under the command of Sam Houston was constantly on the move, while terrified civilians fled with the army, in a melee known as the Runaway Scrape. On March 31, Houston paused his men at Groce's Landing on the Brazos River, and for the next two weeks, the Texians received rigorous military training. Becoming complacent and underestimating the strength of his foes, Santa Anna further subdivided his troops. On April 21, Houston's army staged a surprise assault on Santa Anna and his vanguard force at the Battle of San Jacinto. The Mexican troops were quickly routed, and vengeful Texians executed many who tried to surrender. Santa Anna was taken hostage; in exchange for his life, he ordered the Mexican army to retreat south of the Rio Grande. The Texians forced Santa Anna to sign the Treaty of Velasco, which gave Texas its independence. However, Mexico refused to recognize the Republic of Texas, and intermittent conflicts between the two countries continued into the 1840s. The annexation of Texas as the 28th state of the United States in 1845 led directly to the Mexican–American War.

The Krag–Jørgensen is a repeating bolt-action rifle designed by the Norwegians Ole Herman Johannes Krag and Erik Jørgensen in the late 19th century. It was adopted as a standard arm by Norway, Denmark, and the United States. About 300 were delivered to Boer forces of the South African Republic. A distinctive feature of the Krag–Jørgensen action is its magazine. While many other rifles of its era use an integral box magazine loaded by a charger or stripper clip, the magazine of the Krag–Jørgensen is integral with the receiver (the part of the rifle that houses the operating parts), featuring an opening on the right hand side with a hinged cover. Instead of a charger, single cartridges are inserted through the side opening, and are pushed up, around, and into the action by a spring follower. Later, similar to a charger, a claw type clip would be made for the Krag that allowed the magazine to be loaded all at once, also known as the Krag "speedloader magazine". The design presents both advantages and disadvantages compared with a top-loading "box" magazine. Normal loading was one cartridge at a time, and this could be done more easily with a Krag than a rifle with a "box" magazine. In fact, several cartridges can be dumped into the opened magazine of a Krag at once with no need for careful placement, and when shutting the magazine-door the cartridges are forced to line up correctly inside the magazine. The design was also easy to "top off", and unlike most top-loading magazines, the Krag–Jørgensen's magazine could be topped up without opening the rifle's bolt. The Krag–Jørgensen is a popular rifle among collectors, and is valued by shooters for its smooth action.

The Spanish–American War (April 21 – August 13, 1898) was fought between Spain and the United States in 1898. It began with the sinking of the USS Maine in Havana Harbor in Cuba, and resulted in the U.S. acquiring sovereignty over Puerto Rico, Guam, and the Philippines, and establishing a protectorate over Cuba. It represented U.S. intervention in the Cuban War of Independence and Philippine Revolution, with the latter later leading to the Philippine–American War. The Spanish–American War brought an end to almost four centuries of Spanish presence in the Americas, Asia, and the Pacific; the United States meanwhile not only became a major world power, but also gained several island possessions spanning the globe, which provoked rancorous debate over the wisdom of expansionism. The 19th century represented a clear decline for the Spanish Empire, while the United States went from a newly founded country to a rising power. In 1895, Cuban nationalists began a revolt against Spanish rule, which was brutally suppressed by the colonial authorities. W. Joseph Campbell argues that yellow journalism in the U.S. exaggerated the atrocities in Cuba to sell more newspapers and magazines, which swayed American public opinion in support of the rebels. But historian Andrea Pitzer also points to the actual shift toward savagery of the Spanish military leadership, who adopted the brutal reconcentration policy after replacing the relatively conservative Governor-General of Cuba Arsenio Martínez Campos with the more unscrupulous and aggressive Valeriano Weyler, nicknamed "The Butcher." President Grover Cleveland resisted mounting demands for U.S. intervention, as did his successor William McKinley. Though not seeking a war, McKinley made preparations in readiness for one. In January 1898, the U.S. Navy armored cruiser USS Maine was sent to Havana to provide protection for U.S. citizens. After the Maine was sunk by a mysterious explosion in the harbor on February 15, 1898, political pressures pushed McKinley to receive congressional authority to use military force. On April 21, the U.S. began a blockade of Cuba, and soon after Spain and the U.S. declared war. The war was fought in both the Caribbean and the Pacific, where American war advocates correctly anticipated that U.S. naval power would prove decisive. On May 1, a squadron of U.S. warships destroyed the Spanish fleet at Manila Bay in the Philippines and captured the harbor. The first U.S. forces landed in Cuba on June 10 in the island's southeast, moving west and engaging in the Battles of El Caney and San Juan Hill on July 1 and then destroying the Spanish fleet and capturing Santiago de Cuba on July 17. On June 20, the island of Guam surrendered without resistance, and on July 25, U.S. troops landed on Puerto Rico, of which a blockade had begun on May 8 and where fighting continued until an armistice was signed on August 13. The war formally ended with the 1898 Treaty of Paris, signed on December 10 with terms favorable to the U.S. The treaty ceded ownership of Puerto Rico, Guam, and the Philippines to the U.S., and set Cuba up to become an independent state in 1902, although in practice it became a U.S. protectorate. The cession of the Philippines involved payment of $20 million ($770 million today) to Spain by the U.S. to cover infrastructure owned by Spain. In Spain, the defeat in the war was a profound shock to the national psyche and provoked a thorough philosophical and artistic reevaluation of Spanish society known as the Generation of '98.

The Ypiranga Incident occurred on April 21, 1914, at the port of Veracruz in Mexico during the Mexican Revolution. Ypiranga was a German steamship that was commissioned to transport arms and munitions to the Mexican federal government under Victoriano Huerta. The United States had placed Mexico under an arms embargo to stifle the flow of weaponry to the war-torn state, then in the throes of civil war, forcing Huerta's government to look to Europe and Japan for armaments. Ypiranga tried to enter the harbor at Veracruz to unload on the first day of the US occupation but was detained by US troops who were ordered by President of the United States Woodrow Wilson to enforce the arms embargo he had placed on Mexico. There was neither a declaration of war on Mexico by the United States nor a formal blockade on its ports, thus the detention of Ypiranga was not legal and she was released. She proceeded to a port where the US military was absent, Puerto México (modern-day Coatzacoalcos, Veracruz), and was able to offload her cargo to Huerta's officials.

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.

Al-Baqi Cemetery, also known as Jannat al-Baqi or Baqi al-Gharqad, is the first and oldest Islamic cemetery in Medina, located southeast of the Prophet's Mosque, in the Hejaz region of present-day Saudi Arabia. It contains the graves of numerous members of the Prophet Muhammad's family, his companions, and other prominent figures from early Islam. The cemetery is significant in both Sunni and Shia Islam as it contains the graves of four of the Twelve Imams, and prominent figures revered in Sunni Islam.

The Loch Ness Monster (Scottish Gaelic: Uilebheist Loch Nis), known affectionately as Nessie, is a mythical creature in Scottish folklore that is said to inhabit Loch Ness in the Scottish Highlands. It is often described as large, long-necked, and with one or more humps protruding from the water. Popular interest and belief in the creature has varied since it was brought to worldwide attention in 1933. Evidence of its existence is anecdotal, with a number of disputed photographs and sonar readings. The scientific community explains alleged sightings of the Loch Ness Monster as hoaxes, wishful thinking, the misidentification of known animals, mundane objects, and other recognized natural phenomena. The pseudoscience and subculture of cryptozoology has placed particular emphasis on the creature.

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 National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1891 until it adopted its current name in 1970.

United Nations Security Council Resolution 47, adopted on 21 April 1948, concerns the resolution of the Kashmir conflict. After hearing arguments from both India and Pakistan, the Council increased the size of the UN Commission created by the former Resolution 39 to five members, instructed the Commission to go to the subcontinent and help the governments of India and Pakistan restore peace and order to the region and prepare for a plebiscite to decide the fate of Kashmir. Secondly, the Resolution recommended a three-step process for the resolution of the dispute. In the first step, Pakistan was asked to withdraw all its nationals that entered Kashmir for the sake of fighting. In the second step, India was asked to progressively reduce its forces to the minimum level required for law and order. In the third step, India was asked to appoint a plebiscite administrator nominated by the United Nations who would conduct a free and impartial plebiscite. The resolution was adopted paragraph by paragraph; no vote on the resolution as a whole was taken. Both India and Pakistan raised objections to the Resolution. However, they welcomed mediation by the UN Commission. Through its mediation, the Commission amplified and amended the Security Council Resolution, adopting two resolutions of its own, which were accepted by both India and Pakistan. Subsequently, a cease-fire was achieved by the Commission at the beginning of 1949. However, a truce was not achieved due to disagreements over the process of demilitarisation. After considerable efforts, the Commission declared its failure in December 1949.

Administrative Professionals Day is a day observed yearly in a small number of countries. It is not a public holiday in any of them. In some countries, it falls within Administrative Professionals Week. The day recognizes the work of secretaries, administrative assistants, executive assistants, personal assistants, receptionists, client services representatives, and other administrative support professionals. Typically, administrative professionals are given cards, flowers, chocolates, and lunches.

United Air Lines Flight 736 was a scheduled American transcontinental passenger service flown daily by United Airlines between Los Angeles and New York City. On April 21, 1958, the airliner assigned to the flight, a Douglas DC-7 with 47 on board, was flying over Clark County, Nevada in clear weather when it was involved in a daytime mid-air collision with a United States Air Force fighter jet crewed by two pilots. Both aircraft fell out of control from 21,000 feet (6,400 m) and crashed into unpopulated desert terrain southwest of Las Vegas, leaving no survivors. The loss of Flight 736, one of a series of 1950s mid-air collisions involving passenger aircraft in American skies, helped usher-in widespread improvements in air traffic control within the United States, and led to a sweeping reorganization of federal government aviation authorities.

Brasília is the capital city of Brazil and the Federal District. Located in the Brazilian Highlands in the country's Central-West region, it was founded by President Juscelino Kubitschek on 21 April 1960, to replace Rio de Janeiro as the national capital. Brasília is Brazil's third-most populous city after São Paulo and Rio de Janeiro, with a population of 2.8 million. Among major Latin American cities, it has the highest GDP per capita.

The Century 21 Exposition was a world's fair held April 21, 1962, to October 21, 1962, in Seattle, Washington, United States. Nearly 10 million people attended the fair during its six-month run.

The Universal House of Justice is the international governing body of the Baháʼí Faith. It was envisioned by Baháʼu'lláh, the founder of the Baháʼí Faith, as an institution that could legislate on issues not already addressed in the Baháʼí writings, providing flexibility for the Baháʼí Faith to adapt to changing conditions. It was first elected in 1963, and subsequently every five years, by delegates consisting of the members of Baháʼí National Spiritual Assemblies throughout the world.

The Transit system, also known as NAVSAT or NNSS, was the first satellite navigation system to be used operationally. The radio navigation system was primarily used by the U.S. Navy to provide accurate location information to its Polaris ballistic missile submarines, and it was also used as a navigation system by the Navy's surface ships, as well as for hydrographic survey and geodetic surveying. Transit provided continuous navigation satellite service from 1964, initially for Polaris submarines and later for civilian use as well. In the Project DAMP Program, the missile tracking ship USAS American Mariner also used data from the satellite for precise ship's location information prior to positioning its tracking radars.

The 1964 New York World's Fair was an international exposition at Flushing Meadows–Corona Park in Queens, New York City, United States. The fair included exhibitions, activities, performances, films, art, and food presented by 80 nations, 24 U.S. states, and nearly 350 American companies. The five sections of the 646-acre (261 ha) fairground were the Federal and State, International, Transportation, Lake Amusement, and Industrial areas. The fair's theme was "Peace through Understanding", and its symbol was the Unisphere, a stainless-steel model of Earth. Initially, the fair had 139 pavilions, and 34 concessions and shows.

Rastafari is an Abrahamic religion that developed in Jamaica during the 1930s. It is classified as both a new religious movement and a social movement by scholars of religion. There is no central authority in control of the movement and much diversity exists among practitioners, who are known as Rastafari, Rastafarians, or Rastas.

A destructive tornado outbreak affected much of the Midwestern United States on April 21, 1967, in particular the towns of Belvidere and Oak Lawn, Illinois, United States. It was the largest tornado outbreak of 1967 and has been described by NWS Chicago as "Northern Illinois' worst tornado disaster". The outbreak produced numerous and significant (F2+) tornadoes, with ten of them in Illinois alone. Included was one of just six documented violent (F4/F5) tornadoes in the Chicago metropolitan area since the area was first settled.

John Watts Young was an American astronaut, naval officer and aviator, test pilot, and aeronautical engineer. He became the ninth person to walk on the Moon as commander of the Apollo 16 mission in 1972.

The Vietnam War was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam and South Vietnam and their allies. North Vietnam was supported by the Soviet Union and China, while South Vietnam was supported by the United States and other anti-communist nations. The conflict was the second of the Indochina wars and a proxy war of the Cold War. The Vietnam War was one of the postcolonial wars of national liberation, a theater in the Cold War, and a civil war, with civil warfare a defining feature from the outset. Direct US military involvement escalated from 1965 until US forces were withdrawn in 1973. The fighting spilled into the Laotian and Cambodian civil wars, which ended with all three countries becoming communist in 1975.

Annie is a musical with music by Charles Strouse, lyrics by Martin Charnin, and a book by Thomas Meehan. It is based on the 1924 comic strip Little Orphan Annie by Harold Gray. The original Broadway production opened in 1977 and ran for nearly six years, setting a record for the Alvin Theatre. It spawned numerous productions in many countries, as well as national tours, and won seven Tony Awards, including for Best Musical. The musical's songs "Tomorrow" and "It's the Hard Knock Life" are among its most popular musical numbers.

Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play beginning when a player on the fielding team, called the pitcher, throws a ball that a player on the batting team, called the batter, tries to hit with a bat. The objective of the offensive team is to hit the ball into the field of play, away from the other team's players, allowing its players to run the bases, having them advance counter-clockwise around four bases to score what are called "runs". The objective of the defensive team is to prevent batters from becoming runners, and to prevent runners advancing around the bases. A run is scored when a runner legally advances around the bases in order and touches home plate.

The Covenant, the Sword, and the Arm of the Lord (CSA) was a far-right survivalist anti-government militia that advocated for Christian Identity and was active in the United States during the 1970s and early 1980s. The CSA developed from a Baptist congregation, the Zarephath-Horeb Community Church, which was founded in 1971 in Pontiac, Missouri. Over time, Zarephath-Horeb evolved into an extremist militant group and it was rechristened the CSA. The group operated at a large compound in northern Arkansas, known as "the Farm.”

The Liberation Tigers of Tamil Eelam was a Tamil militant organization, that was based in northern and eastern Sri Lanka. LTTE sought to create an independent Tamil state called Tamil Eelam in the northeast of the island in response to violent persecution and discriminatory policies against Sri Lankan Tamils by the Sinhalese-dominated Sri Lankan government.

Protests led by students and workers, known in China as the June Fourth Incident, were held in Tiananmen Square in Beijing, China, from 15 April to 4 June 1989. After weeks of unsuccessful attempts between the demonstrators and the Chinese government to find a peaceful resolution, the Chinese government initiated martial law in late May and deployed troops to occupy the square on the night of 3 June in what is referred to as the Tiananmen Square massacre. The events are sometimes called the '89 Democracy Movement, the Tiananmen Square Incident, or the Tiananmen uprising. The Chinese government terms the events the political turmoil between the spring and summer of 1989.

La Paz, officially Nuestra Señora de La Paz, is the seat of government of Bolivia. With 755,732 residents as of 2024, it is the third-most populous city in Bolivia. Its metropolitan area, which includes the neighboring city of El Alto, and other smaller towns, is the second most populous urban area in Bolivia, with a population of 2.2 million, after Santa Cruz de la Sierra with a population of 2.3 million. The city is also the capital of the department of the same name.

The Jokela rail accident occurred on 21 April 1996, at 07:08 local time in Tuusula, Finland, approximately 50 kilometres (30 mi) north of Helsinki. Four people were killed and 75 injured when express train P82 from Oulu, bound for Helsinki, derailed in heavy fog. The overnight sleeper train was carrying 139 passengers and five crew members. The official investigation found the accident was caused by overspeeding through a slow-speed turnout.

The Agreement between Ukraine and Russia on the Black Sea Fleet in Ukraine, widely referred to as the Kharkiv Pact or Kharkov Accords, was a treaty between Ukraine and Russia whereby the Russian lease on naval facilities in Crimea was extended beyond 2017 until 2042, with an additional five-year renewal option in exchange for a multiyear discounted contract to provide Ukraine with Russian natural gas.

On 21 April 2012 at 18:30 local time, two trains were involved in a head-on collision at Westerpark, near Sloterdijk, in the west of Amsterdam, Netherlands. Approximately 117 people were injured, one of whom later died in hospital. The collision is thought to have been caused by the driver of one of the trains passing a red signal.

On 21 April 2019, Easter Sunday, three churches in Sri Lanka and three luxury hotels in the commercial capital, Colombo, were targeted in a series of coordinated Islamic State (IS)-related terrorist suicide bombings. Later that day, two smaller explosions occurred at a housing complex in Dematagoda and a guest house in Dehiwala. A total of 269 people were killed, with over 200 of them being Christians, including at least 45 foreign nationals, three police officers, and nine suicide bombers. An additional 500 were injured. The church bombings were carried out during Easter services in Negombo, Batticaloa and Colombo; the hotels bombed included the Shangri-La, Cinnamon Grand, Kingsbury and Tropical Inn. According to the State Intelligence Service, a second wave of attacks was planned, but was prevented due to government raids.

The Indonesian Navy is the naval branch of the Indonesian National Armed Forces. It was founded on 10 September 1945 and has a role to patrol Indonesia's lengthy coastline, to enforce and patrol the territorial waters and Exclusive Economic Zone (EEZ) of Indonesia, to protect Indonesia's maritime strategic interests, to protect the islands surrounding Indonesia, and to defend against seaborne threats.