August 13 is the 225th day of the year (226th in leap years) in the Gregorian calendar; 140 days remain until the end of the year.
1521 – After an extended siege, forces led by Spanish conquistador Hernán Cortés capture Tlatoani Cuauhtémoc and conquer the Aztec capital of Tenochtitlan.
1532 – Union of Brittany and France: The Duchy of Brittany is absorbed into the Kingdom of France.
1536 – Buddhist monks from Kyoto, Japan's Enryaku-ji temple set fire to 21 Nichiren temples throughout Kyoto in what will be known as the Tenbun Hokke Disturbance.
1553 – Michael Servetus is arrested by John Calvin in Geneva, Switzerland as a heretic.
1624 – The French King Louis XIII appoints Cardinal Richelieu as prime minister.
1645 – Sweden and Denmark sign Peace of Brömsebro.
1650 – Colonel George Monck of the English Army forms Monck's Regiment of Foot, which will later become the Coldstream Guards.
1704 – War of the Spanish Succession: Battle of Blenheim: English and Imperial forces are victorious over French and Bavarian troops.
1724 – Johann Sebastian Bach leads the first performance of Nimm von uns, Herr, du treuer Gott, a chorale cantata on a famous tune.
1779 – American Revolutionary War: The Royal Navy defeats the Penobscot Expedition with the most significant loss of United States naval forces prior to the attack on Pearl Harbor.
1792 – King Louis XVI of France is formally arrested by the National Tribunal, and declared an enemy of the people.
1806 – Battle of Mišar during the Serbian Revolution begins. The battle ends two days later with a Serbian victory over the Ottomans.
1814 – The Convention of London, a treaty between the United Kingdom and the United Netherlands, is signed in London.
1868 – The 8.5–9.0 Arica earthquake struck southern Peru with a maximum intensity of XI (Extreme), causing 25,000+ deaths and a destructive basin wide tsunami that affected Hawaii and New Zealand.
1889 – William Gray of Hartford, Connecticut is granted United States Patent Number 408,709 for 'Coin-controlled apparatus for telephones.'
1898 – Spanish– American War: Spanish and American forces engage in a mock battle for Manila, after which the Spanish commander surrendered in order to keep the city out of Filipino rebel hands.
1898 – Carl Gustav Witt discovers 433 Eros, the first near-Earth asteroid to be found.
1900 – The steamer Deutschland of Hamburg America Lines set a new record for the eastward passage when it docked on Plymouth, England, five days, 11 hours and 45 minutes after sailing from New York.
1905 – Norwegians vote to end the union with Sweden.
1906 – The all Black infantrymen of the U.S. Army's 25th Infantry Regiment are accused of killing a White bartender and wounding a White police officer in Brownsville, Texas, despite exculpatory evidence; all are later dishonorably discharged. (Their records were later restored to reflect honorable discharges but there were no financial settlements.)
1913 – First production in the UK of stainless steel by Harry Brearley.
1918 – Women enlist in the United States Marine Corps for the first time. Opha May Johnson is the first woman to enlist.
1918 – Bayerische Motoren Werke AG (BMW) established as a public company in Germany.
1920 – Polish–Soviet War: The Battle of Warsaw begins and will last till August 25. The Red Army is defeated.
1942 – Major General Eugene Reybold of the U.S. Army Corps of Engineers authorizes facilities that would the Manhattan Project.
1944 – World War II: German troops begin the pillage and razing of Anogeia in Crete that would continue until September 5.
1960 – The Central African Republic declares independence from France.
1961 – Cold War: East Germany closes the border between sectors of Berlin to thwart attempts to escape to the West, and construction of the Berlin Wall is started.The day is known as Barbed Wire Sunday.
1964 – Peter Allen and Gwynne Evans are hanged, the last people executed in the United Kingdom.
1967 – Two young women became the first fatal victims of grizzly bear attacks in the 57year history of Montana's Glacier National Park in separate incidents.