Warships were no novelty to St. Mawes Castle, which has brooded over the waters of Falmouth Harbor for 400 years. The LSTs (Landing Ship, Tank) shown entering the harbor behind a U.S. minesweeper of the Revon class were a 1944 expression of the kind of invasive naval forces which this castle was built to repulse. But the castle would be about as much use as an umbrella against these ships.

When King Henry VIII of England constructed this artillery fort (as well as Pendennis Castle across the bay and many others) as part of his new coastal defense system in the 16th century, his measures were sweeping and extraordinary. Although a national monument in peacetime, the castle was used as a Royal Air Force auxiliary headquarters during World War II.