High Quality Content by WIKIPEDIA articles! The military career of Benedict Arnold from 1777 to 1779 was marked by two important events in his career. In July 1777, Arnold was assigned to the Continental Army`s Northern Department, where he played pivotal roles in bringing about the failure of British Brigadier General Barry St. Leger`s siege of Fort Stanwix and the American success in the battles of Saratoga, which fundamentally altered the course of the war.