In December 1941, a friend of design duo Charles and Ray Eames mentioned that the United States Navy—recently attacked at Pearl Harbor—needed to replace their leg splints, which had often done more harm than good. Building on years of DIY experiments with plywood—thin sheets of wood pressed together—the Eameses created a splint that could withstand combat conditions and comfortably accommodate an injured leg. With some 150,000 manufactured during World War II, the splint proved that plywood could be produced quickly and cheaply, paving the way for the postwar furniture that would make the Eameses famous.