After receiving military training in his native Poland and France, he resigned his commission due to poor advancement prospect. Offering his assistance to the Americans, he helped fortify the Delaware River in 1776, earning himself the rank of colonel. That winter, he planned the building of Fort Mercer, and the next spring headed north with General Gates, becoming commander of the northern army and building fortifications which helped win the battle of Saratoga. In 1780, he worked on building defenses for West Point, then headed south when Gates was appointed command of the Southern Department. Serving under Nathaniel Greene, he distinguished himself in the Race to the Dan River, and at Charleston, but mishandled the siege of Ninety-Six. Following the war, he was granted American citizenship but returned home to Poland. Back home he resisted partition, and attempted to liberate the nation afterward.