Thanksgiving didn't become an annual national holiday until the days of Abraham Lincoln, but at the time of the nation's founding, religious feasts (and fasts) of thanksgiving were a regular thing. Both the Continental Congress and Gen. George Washington declared days of public thanksgiving during the Revolutionary War after big victories. And in 1779, Virginia's wartime governor, Thomas Jefferson, signed a proclamation declaring Thursday, Dec. 9, "a day of publick and solemn thanksgiving and prayer to Almighty God."