Behind the scenes during the Second World War, agreements were negotiated for the safe exchange and repatriation of wounded or gravely ill prisoners, ‘Protected Personnel’, diplomats, civilians and alien internees, a little-known dimension of the war. Conducted under the oversight of the International Red Cross and through neutral intermediaries, exchanges were arranged individually between Allied nations and the Axis belligerents. A group of some 50 ships, many 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, receipt and observance of ‘safe passage’ commands to the armed units in their paths. This book describes these special ships and details the exchange missions they took part in.