Born in Flanders, Marthe Cnockaert McKenna (1892-1986) was recruited in 1915, during World War I, to an Anglo-Belgian espionage ring. Her cover was as a nurse, and the Germans awarded her the Iron Cross for her hospital work. After a period as a double agent she was apprehended by them and sentenced to death. The sentence was not carried out and she was released from prison at the Armistice in 1918. Cited for heroism by Winston Churchill, she received the French and Belgian Legions of Honour. The star Madeline Carroll portrayed her in Victor Saville's 1933 thriller, I Was A Spy. She became a British subject and during World War II the Nazis included her in The Black Book of leaders to be arrested when they invaded England. This book appeared in 1934 and was perhaps her most forthright and psychologically interesting work, showing signs of the influence and collaboration of "Jock" McKenna, the British Army officer she had married.