Would four-inch shells penetrate destroyer armor?
Short answerDestroyers have hull plating rather than an armor belt. The issue is the explosive damage a shell can cause after entering.
NotesThe destroyers discussed have steel hull plating, with thicker plating in some areas, rather than armor. Penetration therefore leaves the question of how much damage a shell causes inside the hull. A 4.7-inch or five-inch shell could produce an explosion large enough to tear open the hull from within. A smaller shell might lack the explosive power to cause the same damage.