On August 11:
3114 BC The Mesoamerican Long Count calendar, used by several pre-Columbian Mesoamerican civilizations, notably the Mayans, began.
480 BC Greco-Persian Wars: Battle of Artemisium – the Persians achieved a naval victory over the Greeks in an engagement fought near Artemisium.
355 Claudius Silvanus, accused of treason, proclaimed himself Roman Emperor against Constantius II.
1786 Captain Francis Light established the British colony of Penang.
1804 Francis II assumed the title of first Emperor of Austria.
1858 First ascent of the Eiger.
1892 Hugh MacDiarmid, Scottish poet, was born (d. 1978).
1897 Enid Blyton, English author, was born (d. 1968).
1918 World War I: Battle of Amiens ended.
1919 Constitution of Weimar Republic adopted.
1921 Alex Haley, American writer, was born (d. 1992).
1929 Babe Ruth became the first baseball player to hit 500 home runs in his career with a home run at League Park in Cleveland, Ohio.
1929 The Bud Billiken Parade and Picnic began its annual tradition, which is now the oldest and largest African American parade in the United States.
1933 Jerry Falwell, American preacher, was born (d. 2007).
1934 First civilian prisoners arrived at Federal prison on Alcatraz Island.
1942 Mike Hugg, British musician (Manfred Mann), was born.
1942 Actress Hedy Lamarr and composer George Antheil received a patent for a frequency hopping, spread spectrum communication system that later became the basis for modern technologies in wireless telephones and Wi-Fi.
1952 Bob Mothersbaugh AKA Bob 1, American musician (Devo), was born.
1952 Hussein proclaimed king of Jordan.
1960 Chad declared independence.
1962 The country’s first roll-on roll-off (RO-RO) ferry, New Zealand Railways’ Aramoana entered service between Wellington and Picton.
1965 The Watts riots began in Watts area of Los Angeles.
1972 The last United States ground combat unit left South Vietnam.
1975 Governor Mário Lemos Pires of Portuguese Timor abandoned the capital Dili, following a coup by the Timorese Democratic Union (UDT) and the outbreak of civil war between UDT and Fretilin.
1982 A bomb exploded on Pan Am Flight 830, en route from Tokyo to Honolulu, killing one teenager and injuring 15 passengers.
1988 Al-Qaeda was formed.
1999 The Salt Lake City Tornado tore through the downtown district of the city, killing one.
2003 NATO took over command of the peacekeeping force in Afghanistan, marking its first major operation outside Europe in its 54-year-history.
2003 – Jemaah Islamiyah leader Riduan Isamuddin, better known as Hambali, was arrested in Bangkok.
2003 – A heat wave in Paris resulted in temperatures rising to 112°F (44° C), leaving about 144 people dead.
Sourced from NZ History Online & Wikipedia