August 21 Through History

Explanation: Vincenzo Peruggia had taken part in fitting protective glass panels on the painting, which allowed him to learn the layout of the place. The painting stayed hidden in his Florentine apartment for two years before being recovered in 1913, when Peruggia tried to sell it to an antique dealer.

Explanation: Lake Nyos is a volcanic lake known as 'meromictic', capable of accumulating large amounts of dissolved CO2 in its depths. The 1986 explosion is one of the rare documented cases of a limnic eruption, a natural phenomenon where the lake suddenly releases its gases to the surface, asphyxiating all life within a radius of several kilometers.

Explanation: Hawaii had been an American territory since 1898, the year the United States annexed it following the fall of the Hawaiian monarchy. This territorial status meant its inhabitants had no representation in the federal Congress and did not vote in presidential elections. Alaska had become the 49th state a few months earlier, in January 1959.

Explanation: The Dumbarton Oaks Conference brought together representatives from the United States, the United Kingdom, the USSR, and China. It resulted in a preliminary document that served as the basis for the United Nations Charter, signed in San Francisco in June 1945. The name comes from the historic estate in Washington D.C. where the meeting took place.

Explanation: Count Basie is famous for his minimalist piano style, using few notes but with a sharp sense of rhythm and swing. His big band, founded in Kansas City in the 1930s, remained one of the most influential in the history of jazz. He was notably one of the pioneers of Kansas City jazz, a variant of swing with very strong blues roots.

Explanation: The invasion was led by the forces of the Warsaw Pact under Soviet command, also involving troops from Poland, Hungary, Bulgaria, and East Germany. The Prague Spring, led by Alexander Dubček, attempted to establish a "socialism with a human face". The intervention was justified by the Brezhnev Doctrine, which asserted the Soviet right to intervene in any socialist country threatening the communist order.

Explanation: Philip Augustus is best known for his victory at the Battle of Bouvines in 1214, which consolidated Capetian power against a coalition bringing together England, the Germanic Empire, and Flanders. He is also known for having considerably expanded the royal domain and for launching the construction of the Paris city wall and the first Louvre castle.

Explanation: Nat Turner's revolt was one of the most significant slave rebellions in American history. It caused around 60 white casualties and led to the execution of Turner and his accomplices. Beyond the immediate crackdown, the insurrection pushed many Southern states to pass even more restrictive laws, including ones banning the literacy of enslaved people, which was seen as dangerous to the established order.

Explanation: Latvia had been annexed by the USSR in 1940, as part of the Molotov-Ribbentrop Pact signed between Nazi Germany and the Soviet Union. It had briefly been occupied by Germany between 1941 and 1944. The 1991 declaration of independence came in the context of the attempted coup against Gorbachev in Moscow, which hastened the dissolution of the USSR.

Explanation: Sergey Brin and Larry Page met at Stanford University in California, where both were PhD students in computer science. It was in this academic setting that they developed the PageRank algorithm, which gave birth to the Google search engine, officially founded in 1998 in a garage in Menlo Park. Stanford is often cited as the birthplace of many Silicon Valley companies.