US Pillbox

The pillbox was a hardened enclosure providing excellent protection, made of such durable materials as concrete and rebar.
The Allies installed numerous bunkers along the Maginot Line – the system of French combat fortifications along the German border. It is believed that the Maginot Line was the most powerful and well-equipped line of defense in all of World War II. It featured fourteen bunkers per kilometer, with a wall thickness of 3.5 to 4 meters of fortified concrete, interconnected into a unified whole by a system of underground railways, galleries and trenches, complete with power stations, warehouses, hospitals, headquarters and communication centers.
Nevertheless, these defenses stood broken for several hours, after they were stormed by a German infantry assault supported with air and artillery – and without the aid of tanks.