This is the compelling story of the 10,000 Germans and Austrians who fled Nazi persecution and joined the British Forces in their fight against Hitler during the Second World War. They began arriving in Britain in 1933 and at the outbreak of war on 3 September 1939 became 'enemy aliens'. Swearing allegiance to King George VI, they volunteered to serve in the British Forces and joined the only unit open to them: the non-combatant Pioneer Corps. Known affectionately as 'the King's most loyal enemy aliens', most were Jews, but a significant number were political opponents of the Nazi regime and so-called 'degenerate artists'. With one or two exceptions, these refugees in uniform did not receive British nationality until 1946-7.

More than 10,000 men enlisted in the Pioneer Corps direct from internment camps in Britain, Canada and Australia after the autumn of 1940, but many soon became disillusioned with digging trenches and laying railway track. They wanted the chance to join the fight against Hitler and their opportunity came in 1942-3 when the British government permitted enemy aliens to enlist in fighting units.

They transferred to the Royal Armoured Corps, Commandos, Parachute Regiment, and infantry regiments, as well as the Royal Navy and RAF. Many were engaged in special operations behind enemy lines with the SOE and SAS, and in intelligence work with the Army Intelligence Corps. Women served in the ATS and Women's Auxiliary Air Force.

In this revealing insight into a little-known aspect of British wartime history, Helen Fry documents the stories of those who joined the British forces and fought for King and adopted Country - most of which are published here for the first time.