service of the militia

Upon returning to Boston in 1776, Revere was commissioned a major of infantry in the Massachusetts militia in that April, and transferred to the artillery a month later. In November he was promoted to lieutenant colonel, and was stationed at Castle William, defending Boston harbor. He was generally second or third in the chain of command, and on several occasions he was given command of the fort. He applied his engineering skills to maintaining the fort's armaments, even designing and building a caliper to accurately measure cannon balls and cannon bore holes. The service at Castle William was relatively isolated, and personality friction prompted some men to file complaints against Revere. The boredom was alleviated in late August 1777 when Revere was sent with a troop of soldiers to escort prisoners taken in the Battle of Bennington to Boston, where they were confined on board prison ships, and again in September when he was briefly deployed to Rhode Island.