He acted as leader of the Culper Ring during the war, a celebrated network of spies in New York where major British forces were based.

[1][2] He graduated from Yale in 1773, where he was a member of Brothers in Unity[3] and was a classmate and close friend of the American Revolutionary War spy Nathan Hale.

[2] He was given the position of director of military intelligence by George Washington after Nathaniel Sackett was relieved of his duties because he did not gain any ground from the enemy.

[5] Tallmadge was in charge of bringing intelligence from British-controlled New York to the Continental army, and he did so by assembling a network of spies known as the Culper Ring, with the help of Abraham Woodhull and Robert Townsend.

On November 21, 1780, Tallmadge and his dragoons rowed across Long Island Sound from Fairfield, Connecticut, to Cedar Beach in Mount Sinai, New York.

Washington, on hearing the news, sent the following letter to Tallmadge: I have received with much pleasure the report of your successful enterprise upon fort St. George, and was pleased with the destruction of the hay at Coram, which must be severely felt by the enemy at this time.

He was admitted as an original member of The Society of the Cincinnati in the state of Connecticut when it was established in July 1783[8] and brevetted to the rank of lieutenant colonel on September 30, 1783.

[18] In 1829, Tallmadge was among a group of Federalists who defended Uriah Tracy against accusations by John Quincy Adams and William Plumer.

[23] Tallmadge is portrayed by Dave Morrissey, Jr., in the 2017 feature film One Life to Give and its sequel Traitor created by TBR News Media.