Battery Irwin, the southernmost of the Endicott Era batteries built at Fort Monroe. Built from 1900 to 1903, it was named for First Lieutenant Douglas S. Irwin of the 3rd US Infantry, who fought against the Indians in Florida, and was killed at the battle of Monterey in the Mexican War, 1846.

While researching Battery Irwin's name, I also found a Rear Admiral John Irwin of the US Navy, who fought with great success on the USS Wabash during the US Civil War, and who died in 1901...I figured he was a slam dunk for the guy after whom this battery was named, but it would make sense that it'd be an Army guy, not a Navy guy, since the Coast Artillery was an Army establishment. Sorry, Rear Admiral John!