Fort Griswold, built in Groton between 1775 and 1778 on high ground above the Thames River, defended New London’s port, a Revolutionary War supply center and privateering base, by commanding ships entering the river. It is most closely tied to the Battle of Groton Heights in September 1781, when British forces under Benedict Arnold attacked after burning New London and overwhelmed the fort’s defenders. The battle is especially remembered for the death of Lieutenant-Colonel William Ledyard after his surrender. Rebuilt and reused in later eras, including the War of 1812, the fort eventually lost military importance and became a preserved state park with related battlefield landmarks.