Wikipedia:Selected anniversaries/August 18

293 BC - The oldest known Roman temple to Venus was founded, starting the institution of Vinalia Rustica.
1572 - French Wars of Religion: Marguerite de Valois (pictured) was married to Huguenot King Henry of Navarre, in a supposed attempt to reconcile Protestants and Catholics in France.
1868 - Pierre Janssen discovered helium while analyzing the chromosphere during a total eclipse of the sun. This was the first element detected in space before being found on Earth.
1941 - The T-4 Euthanasia Program in Nazi Germany was temporarily halted due to public resistance.
1966 - Vietnam War: A company of the Royal Australian Regiment fought a much larger North Vietnamese unit in the Battle of Long Tan.

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