Fort McClary is a former defensive fortification of the United States military located along the southern coast at Kittery Point, Maine at the mouth of the Piscataqua River.

The Province of Massachusetts Bay voted in 1715 to erect a permanent breastwork of six guns for the defense of the Piscataqua River, during the lead-up to Father Rale's War.

Some sources state that it was intended to protect Maine (then part of Massachusetts) from "unreasonable duties" (taxes) that the governor of New Hampshire was attempting to impose on nearby citizens of other colonies.

The fort was further expanded in the 1840s, probably a consequence of tensions with Great Britain over the disputed border between Maine and New Brunswick which culminated in the bloodless Aroostook War and the 1842 Webster-Ashburton Treaty.

The fort saw active use during the American Civil War, at which time it achieved much of its present structure due to a rebuilding under the third system that was never completed.

[2] Its Civil War garrison notably included Vice President Hannibal Hamlin, who enlisted in Company A of the Maine State Guard as a private and served as a cook in the fort.

A major rebuilding and expansion began in 1863 as part of the third system of fortifications, and the intent was to create a large five-sided fort with one or two tiers of cannon all around.