The first American Congress enacted the first national day of Thanksgiving during the Revolution. (Hat tip to Laura Ingraham)
Saratoga turned the tide of the war -- news of the victory was decisive in bringing France into a full alliance with America. Congress responded to the event by appointing a committee of three that included Samuel Adams, Richard Henry Lee of Virginia and Daniel Roberdeau of Pennsylvania, to draft a report and resolution. The report, adopted Nov. 1, declared Thursday, Dec. 18, as "a day of Thanksgiving" to God, so that "with one heart and one voice the good people may express the grateful feelings of their hearts, and consecrate themselves to the service of their divine benefactor."
On October 3, 1863, in the middle of the dire circumstances of the Civil War, President Abraham Lincoln issued a proclamation that carried on the tradition of giving thanks to God.
I do therefore invite my fellow citizens in every part of the United States, and also those who are at sea and those who are sojourning in foreign lands, to set apart and observe the last Thursday of November next, as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens. And I recommend to them that while offering up the ascriptions justly due to Him for such singular deliverances and blessings, they do also, with humble penitence for our national perverseness and disobedience, commend to His tender care all those who have become widows, orphans, mourners or sufferers in the lamentable civil strife in which we are unavoidably engaged, and fervently implore the interposition of the Almighty Hand to heal the wounds of the nation and to restore it as soon as may be consistent with the Divine purposes to the full enjoyment of peace, harmony, tranquillity and Union.
Have a good time with family and friends and don't eat any more than I would. ;-)