World War II (WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. In a state of "total war", the major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, erasing the distinction between civilian and military resources. Marked by mass deaths of civilians, including the Holocaust (in which approximately 11 million people were killed) and the strategic bombing of industrial and population centres (in which approximately one million were killed, and which included the atomic bombings of Hiroshima and Nagasaki), it resulted in an estimated 50 million to 85 million fatalities. These made World War II the deadliest conflict in human history.

British hardened field defences of World War II were small fortified structures constructed as a part of British anti-invasion preparations. They were popularly known as pillboxes, a reference to their shape.

Design and development

In May 1940, the directorate of Fortifications and Works (FW3) was set up at the War Office under the direction of Major-General G. B. O. Taylor. Its purpose was to provide a number of basic but effective pillbox designs that could be constructed by soldiers and local labour at appropriate defensive locations. In the following June and July FW3 issued six basic designs for rifle and light machine gun, designated Type 22 to Type 27. In addition, there were designs for gun emplacements suitable for either the Ordnance QF 2 pounder or the Hotchkiss 6pdr gun (designated Type 28) and a design for a hardened medium machine gun emplacement.

There were also designs for pillbox-like structures for various purposes including light anti-aircraft positions, observation posts and searchlight positions to illuminate the shoreline. In addition, the Air Ministry provided designs of fortifications intended to protect airfields from troops landing or parachuting. These would not be expected to face heavy weapons so that the degree of protection was less and there was more emphasis on all-round visibility and sweeping fields of fire. Many of these were later reinforced.