The Defence Medal was instituted by the United Kingdom in May 1945, to be awarded to British military and civilian personnel for a range of services in the United Kingdom, and to Commonwealth and British Colonial personnel who served from or outside their home countries in a non-operational area or in an area subject to threat, such as attacks from the air.

[1][5] In the United Kingdom, those eligible included military personnel working in headquarters, on training bases and airfields for the duration of the War in Europe from 3 September 1939 to 8 May 1945, and service by members of the Home Guard during its existence from 14 May 1940 to 31 December 1944.

[1] The length of qualifying service required for the award of the Defence Medal varied, depending on where and in what role an individual served.

Movements by personnel from one territory to another within the defined groups were not regarded as "outside the country of residence" in terms of qualification for the award of the Defence Medal.

[3][6] The obverse, designed by Humphrey Paget,[9] shows the bareheaded effigy of King George VI, facing left.

[3] The reverse, designed by Harold Parker,[9] shows the Royal Crown resting on an oak sapling, flanked by a lion and a lioness above stylised waves.