Patten was commissioned a first lieutenant in Captain John Caldwell's 2nd Company of the 1st Delaware Regiment at the beginning of the American Revolutionary War. He was soon promoted to captain of the 1st Company and in February 1779 and was promoted to the rank of major. He fought in every major battle from the Battle of Long Island until the Battle of Camden, where the Delaware Regiment suffered grievous losses, and he was taken prisoner. Paroled in 1781, after the fighting was over, he is said to have walked home alone in rags from Charleston, South Carolina.