[2] The land was acquired by the U.S. federal government in 1872 and the fort was built from 1898 to 1901 as part of the large-scale Endicott Program.

[2][3][4] The site was a sub-post of Fort Constitution and was named for American Civil War-era Brevet Major General John G. Foster of New Hampshire.

[3] After the American entry into World War I in early 1917, many guns were removed from coast defenses for potential service on the Western Front.

All three 10-inch (254 mm) guns of Battery Bohlen were removed for potential use as railway artillery in October 1917, and were returned to the fort in September 1919.

However, new construction also took place at Fort Foster as part of the general improvement of US coast defenses that began in 1940.