After the victory, the Continental Congress established a Thanksgiving committee to make a recommendation for some form of national celebration of the victory.
In CONGRESS, NOVEMBER 1, 1777, Forasmuch as it is the indispensable duty of all men to adore the superintending providence of Almighty God; to acknowledge with gratitude their obligations to HIM for benefits received. . . . And it having pleased him in his abundant mercy, not only to continue to us the innumerable bounties of his common providence; but also to smile upon us, in the prosecution of a just and necessary war for the defence and establishment of our unalienable rights and liberties: Particularly in that he hath been pleased in so great a measure, to prosper the means used for the support of our troops, and to crown our arms with most signal success: It is therefore recommended to the legislative or executive powers of these United States, to set apart THURSDAY, the eighteenth day of December next for SOLEMN THANKSGIVING and PRAISE: That at one time and with one voice, the good people may express the grateful feelings of their hearts, and consecrate themselves to the service of their DIVINE BENEFACTOR.. . . That it may please him graciously to afford his blessing on the Governments of these States respectively, and prosper the PUBLIC COUNCIL of the whole. To inspire our commanders both by land and sea, and all under them. . . under the providence of Almighty God, to secure for these United States, the greatest of all human blessings, INDEPENDENCE and PEACE. That it may please him, to prosper the trade and manufactures of the people, and the labour of the husbandman. . . To take schools and seminaries of education, so necessary for cultivating the principles of true liberty, virtue and piety, under his nurturing hand: and to prosper the means of religion, for the promotion and enlargement of that kingdom which consisteth "IN RIGHTEOUSNESS, PEACE AND JOY IN THE HOLY GHOST. And it is further recommended, that service, labour, and such recreation as, though at other times innocent . . . may be omitted on so solemn an occasion.I hope they didn't mean football, when they asked that "such recreation as, though at other times innocent . . . may be omitted". That wouldn't do at all. Nope, not at all.
It was the first national Thanksgiving, but it didn't become an annual affair until Lincoln issued his famous proclamation in 1863.
Happy Thanksgiving.