May 20 in History

The Battle of Alfarrobeira took place on 20 May 1449. It was a confrontation between the forces commanded by King Afonso V of Portugal and his uncle Afonso, Duke of Braganza, against the army of the rebellious Peter, Duke of Coimbra. The place was Vialonga, near Lisbon, at the margins of the creek of Alfarrobeira. The result was the clear defeat and death of the Duke of Coimbra and the establishment of the Braganzas as the most powerful House of Portugal.

Vasco da Gama was a Portuguese mariner, explorer and nobleman. His discovery of the first direct maritime route between Europe and India via the Cape of Good Hope and across the Indian Ocean from Malindi in Kenya to Kozhikode was to open up European exploration of, and commerce with, India, and is considered a landmark event and a turning point in world history.

Ignatius of Loyola, venerated as Saint Ignatius of Loyola, was a Spanish Catholic priest and theologian, who, with six companions, founded the religious order of the Society of Jesus (Jesuits), and became its first Superior General, in Paris in 1541.

William Shakespeare wrote sonnets on a variety of themes. When discussing or referring to Shakespeare's sonnets, it is almost always a reference to the 154 sonnets that were first published all together in a quarto in 1609. However, there are six additional sonnets that Shakespeare wrote and included in the plays Romeo and Juliet, Henry V and Love's Labour's Lost. There is also a partial sonnet found in the play Edward III.

The Yangzhou Massacre refers to the mass killing of people in Yangzhou, China, in May, 1645. Commanded by the Manchu prince Dodo, following the collapse of the Ming dynasty, Qing dynasty forces carried out the attack on the port city and its inhabitants, defended by remaining southern Ming forces. The massacre itself lasted a total of six days, which afterwards the burning of bodies continued. The Yangzhou Massacre served as a reminder to Ming loyalists of the threat to resisting Qing authority, and signals part of the transition from the Ming to the Qing.

The Battle of Cartagena de Indias took place during the 1739 to 1748 War of Jenkins' Ear between Spain and Great Britain. The result of long-standing commercial tensions, the war was primarily fought in the Caribbean; the British tried to capture key Spanish ports in the region, including Porto Bello and Chagres in Panama, Havana, and Cartagena de Indias in present-day Colombia.

The Law of 20 May 1802 was a decree passed by First Consul Napoleon of the French First Republic on 20 May 1802 that reinstated slavery. It decreed the reinstatement and continuation of slavery in French colonies reversing the Law of 4 February 1794, which had abolished the institution in all of France's overseas possessions but was only implemented in Saint-Domingue, Guadeloupe and Cayenne.

The American Civil War was a civil war in the United States between the Union and the Confederacy, which was formed in 1861 by states that had seceded from the Union to preserve slavery in the United States, which they saw as threatened because of the election of Abraham Lincoln and the growing abolitionist movement in the North. The war lasted a little over four years, ending with Union victory, the dissolution of the Confederacy and the abolition of slavery, freeing four million African Americans.

Abraham Lincoln was the 16th president of the United States, serving from 1861 until his assassination in 1865. He led the United States through the American Civil War, defeating the Confederate States and playing a major role in the abolition of slavery.

Levi Strauss was a German-born American businessman who founded the first company to manufacture blue jeans. His firm of Levi Strauss & Co. (Levi's) began in 1853 in San Francisco, California.

The Triple Alliance was a defensive military alliance between Germany, Austria-Hungary, and Italy. It was formed on 20 May 1882 and renewed periodically until it expired in 1915 during World War I. Germany and Austria-Hungary had been closely allied since 1879. Italy was looking for support against France shortly after it lost North African ambitions to the French. Each member promised mutual support in the event of an attack by any other great power. The treaty provided that Germany and Austria-Hungary were to assist Italy if it was attacked by France without provocation. In turn, Italy would assist Germany if attacked by France without provocation. In the event of a war between Austria-Hungary and Russia, Italy promised to remain neutral. After the Austro-Hungarian empire and Germany declared war without first being attacked by other nations, Italy did not take part in World War I on the side of the Central Powers and later joined on the side of the Allied Powers.

The history of film chronicles the development of a visual art form created using film technologies that began in the late 19th century.

The 1927 Treaty of Jeddah, formally the Treaty between His Majesty and His Majesty the King of the Hejaz and of Nejd and Its Dependencies was signed between the United Kingdom and Ibn Saud.

Amelia Mary Earhart was an American aviator and aviation pioneer who became one of the most celebrated figures of early flight.

The Battle of Crete, codenamed Operation Mercury, was a major Axis airborne and amphibious operation during World War II to capture the island of Crete. It began on the morning of 20 May 1941, with multiple German airborne landings on Crete. Greek and other Allied forces, along with Cretan civilians, defended the island. After only one day of fighting, the Germans had suffered heavy casualties and the Allied troops were confident that they would defeat the invasion. The next day, through communication failures, Allied tactical hesitation, and German offensive operations, Maleme Airfield in western Crete fell, enabling the Germans to land reinforcements and overwhelm the defensive positions on the north of the island. Allied forces withdrew to the south coast. More than half were evacuated by the British Royal Navy and the remainder surrendered or joined the Cretan resistance. The defence of Crete evolved into a costly naval engagement; by the end of the campaign the Royal Navy's eastern Mediterranean strength had been reduced to only two battleships and three cruisers.

Chiang Kai-shek was a Chinese military commander, revolutionary, and statesman who led the Republic of China (ROC) from 1928 until his death in 1975. His government was based in mainland China until it was defeated in the Chinese Civil War by Mao Zedong's Chinese Communist Party (CCP) in 1949, after which he continued to lead the ROC government on Taiwan.

Operation Redwing was a United States series of 17 nuclear test detonations from May to July 1956. They were conducted at Bikini and Enewetak atolls by Joint Task Force 7 (JTF7). The entire operation followed Project 56 and preceded Project 57. The primary intention was to test new, second-generation thermonuclear weapons. Also tested were fission devices intended to be used as primaries for thermonuclear weapons, and small tactical weapons for air defense. Redwing demonstrated the first United States airdrop of a deliverable hydrogen bomb during test Cherokee. Because the yields for many tests at Operation Castle in 1954 were dramatically higher than predictions, Redwing was conducted using an "energy budget": There were limits to the total amount of energy released, and the amount of fission yield was also strictly controlled. Fission, primarily "fast" fission of the natural uranium tamper surrounding the fusion capsule, greatly increases the yield of thermonuclear devices, and constitutes the great majority of the fallout, as nuclear fusion is a relatively clean reaction.

The discovery of cosmic microwave background radiation constitutes a major development in modern physical cosmology. In 1964, American physicist Arno Allan Penzias and radio-astronomer Robert Woodrow Wilson discovered the cosmic microwave background (CMB), estimating its temperature as 3.5 K, as they experimented with the Holmdel Horn Antenna. The new measurements were accepted as important evidence for a hot early Universe and as evidence against the rival steady state theory as theoretical work around 1950 showed the need for a CMB for consistency with the simplest relativistic universe models. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics for their joint measurement. There had been a prior measurement of the cosmic background radiation (CMB) by Andrew McKellar in 1941 at an effective temperature of 2.3 K using CN stellar absorption lines observed by W. S. Adams. Although no reference to the CMB is made by McKellar, it was not until much later after the Penzias and Wilson measurements, that the significance of this earlier measurement was understood.

The Popular Movement of the Revolution was the ruling political party in Zaire. For most of its existence, it was the only legally permitted party in the country. It was founded by Joseph-Désiré Mobutu on 20 May 1967.

Chuknagar massacre was a massacre of Bengali Hindus committed by the Pakistan Army and local collaborators during the Bangladesh War of Independence in 1971. The massacre took place on 20 May 1971 at Dumuria in Khulna and it was one of the largest massacres during the war.

Human immunodeficiency viruses (HIVs) are two species of Lentivirus that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Without treatment, the average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype.

Radio y Televisión Martí is an international broadcaster based in Miami, Florida, financed by the federal government of the United States through the U.S. Agency for Global Media. It transmits its programs in Spanish to Cuba and its broadcasts can also be heard and viewed worldwide through their website and on shortwave radio frequencies.

Communism is a political and economic ideology whose goal is the creation of a communist society, a socioeconomic order centered on common ownership of the means of production, distribution, and exchange that allocates products in society based on need. A communist society entails the absence of private property and social classes, and ultimately money and the state. Communism is a part of the broader socialist movement.

Timor-Leste, also known as East Timor, officially the Democratic Republic of Timor-Leste, is a country in Southeast Asia. It comprises the eastern half of the island of Timor, the coastal exclave of Oecusse in the island's northwest, and the islands of Atauro and Jaco, for a total land area of 14,950 square kilometres (5,770 sq mi). Timor-Leste shares a land border with Indonesia to the west; Australia is the country's southern neighbour, across the Timor Sea. Dili, on the north coast of Timor, is its capital and largest city.

Mamata Banerjee is an Indian politician and lawyer who is currently serving as the chief minister of West Bengal since 20 May 2011; she is the first woman to hold the office. The founder and president of the All India Trinamool Congress, she previously served as a Union Cabinet Minister and is also the current leader of the house in West Bengal's Legislative Assembly.

The Enhanced Fujita scale is a scale that rates tornado intensity based on the severity of the damage a tornado causes. It is used in the United States, Brazil and France, among other countries. The EF scale is also unofficially used in other countries, including China. The rating of a tornado is determined by conducting a tornado damage survey.

The International System of Units, internationally known by the abbreviation SI, is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce. The SI is coordinated by the International Bureau of Weights and Measures, which is abbreviated BIPM from French: Bureau international des poids et mesures.