A 75 mm weapon is roughly a three-inch gun, making it a small main armament for most warships. The calibre can make more sense on coastal craft, although some vessels in that category carried four-inch guns. The comparison explains why a gun that sounds substantial in another setting occupies the lower end of naval main armament.
Notable Point · 1:49:18-1:49:50
Why 75 mm is small for a warship's main gun
At roughly three inches, a 75 mm gun sits near the small end of naval main armament and is more plausible on coastal craft.