After Benedict Arnold turned his coat red, he proved his worth to the British by launching a devastating attack against the city of Groton, which served as home port for many colonial privateers who were harassing the British navy and guarded the rich port of New London .
Arnold launched his 1781 attack against Fort Griswold (57 Fort St., Groton, 860/449-6877, www.ct.gov/dep , 10 a.m.–5 p.m. daily Memorial Day–Labor Day; 10 a.m.–5 p.m. Sat.–Sun. Labor Day–Columbus Day; grounds open 8 a.m.–sunset year-round, free) on the mouth of the Thames River.
After easily defeating those inside, Arnold purportedly led a massacre, killing half of the 160 defenders as they tried to surrender. In addition to a monument commemorating the battle, a house on the grounds where the wounded were tended has been turned into a small museum of the engagement.