6th October 1973 - Yom Kippur War Begins

Hoping to win back territory lost to Israel during the third Arab-Israeli war, Egyptian and Syrian forces launch a coordinated attack against Israel on Yom Kippur, the holiest day in the Jewish calendar. Taking the Israeli Defense Forces by surprise, Egyptian troops swept deep into the Sinai Peninsula, while Syria struggled to throw occupying Israeli troops out of the Golan Heights.

http://www.history.com