President Abraham Lincoln, “Proclamation of Thanksgiving” (October 3, 1863)
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, tranquility and Union.
Announced 150 years ago on October 3, 1863, this presidential proclamation, widely believed to be written by Secretary of State William Seward, established the precedent for the first American national Thanksgiving Day.