When the American Revolution began in April 1775 Paterson was commissioned as a colonel by the Massachusetts Committee of Safety, and he marched with his militia unit to take part in the Siege of Boston. Paterson's command, the 1st Massachusetts Regiment saw action at the Battle of Bunker Hill. After the British evacuation of Boston, Paterson's regiment took part in the Invasion of Canada and the battles of Trenton and Princeton in New Jersey. On February 21, 1777 Paterson was promoted to brigadier general in the Continental Army.