In April 1775 the American Revolution broke out full-scale at Lexington and Concord in Massachusetts. In March 1776 Patriot forces captured Boston. Their commander, General George Washington, thought the evacuating British force would immediately attempt to capture New York and sent troops to the city, soon followed by himself. Several forts were built by the patriots in the New York City area in June and July 1776, including Fort Washington in northwestern Manhattan and Fort Constitution (later Fort Lee) across the Hudson in the town later named for it. Both forts were just south of the current George Washington Bridge. Fort Lee was named for Patriot general Charles Lee. A chevaux de frise barrier was placed in the Hudson between the two forts to prevent ships passing. Both forts were hastily built and had few defensive features, even lacking ditches. Another fort that proved important was a set of batteries on Nutten Island (now called Governor's Island). Numerous small forts were also built in the city.