Behind the scenes during the Second World War, agreements were negotiated for wounded or gravely ill prisoners and 'Protected Personnel' = diplomats, clergy, civilians and alien internees - to be safely exchanged, a little-known dimension of the war. Conducted under the International Red Cross and neutral intermediaries, exchanges were arranged individually between Allied nations and the Axis belligerents. A group of 36 ships, in special livery, were uniquely engaged in this highly dangerous work, sailing through hostile waters alone and undefended, and conspicuously illuminated at night. Constantly at risk of attack by submarine and aircraft, their safety depended on the transmission and receipt of 'safe passage' commands to the armed units in their paths. This book describes these special ships and details the exchange operations they took part in.