Ornately engraved partly-printed vellum DS, signed “G:o Washington,” one page, 20 x 13.75, December 10, 1785. A Society of Cincinnati membership certificate issued to Thomas Tillotson. In part: "Be it known that Thomas Tillotson Esquire, Physician & Surgeon General to the late Northern Army is a Member of the Society of the Cincinnati; instituted by the Officers of the American Army, at the Period of its Dissolution, as well to commemorate the great Event which gave Independence to North America, as for the laudable Purpose of inculcating the Duty of lying down in Peace Arms assumed for public Defence, and of uniting in Acts of brotherly Affection, and Bonds of perpetual Friendship…In Testimony whereof I, the President of the said Society, have hereunto set my Hand at Mount Vernon." Signed at the conclusion by George Washington as the Society's president and countersigned by Henry Knox as secretary. Handsomely double-matted with a portrait of General Washington to an overall size of 33.75 x 18.75. In very good to fine condition, with overall rippling, and light show-through (and an associated stain) at the top edge from two pieces of archival tape on the reverse.The Society of the Cincinnati was founded in May 1783 as an exclusive fraternal organization for officers who had served at least three years in the Continental military, as well as high-ranking officers in the French military; membership has since been expanded to include the eldest male heirs of original members and descendants of officers who served during the Revolution. Washington was elected as the first President General of the Society in December of 1783 and served until his death in 1799, when he was succeeded by Alexander Hamilton.Society of the Cincinnati documents are quite rare and represent one of the most attractive and desirable formats of all Washington documents available. The recipient of this example, Thomas Tillotson, had served as a first lieutenant and medical surgeon during the Revolution, and had been in direct communication with Tillotson in 1778, requesting his services in the formation of a military and flying hospital for the use and benefit of the troops under the command of Major General Sullivan. A spectacular document signed by the nation's founding father.Format: DS