When the Second World War started, Ryder was serving as a lieutenant commander on . In 1940, he was promoted to commander of the Q-ship which was sunk by a torpedo in the Atlantic, 200 miles west of Ireland; Ryder was adrift for four days before rescue. Appointed commander of the sloop . In early 1941, he went on to captain the "Prince Philippe" a cross-channel steamer converted to a Commando ship, which sank after a collision in the Firth of Clyde. Ryder, now a commander, led the St Nazaire Raid, codenamed Operation Chariot, on 28 March 1942. This was a successful operation to destroy the "Normandie Dock" in the German naval base in the town. The stated aim of the operation was to deny large German ships, particularly the German battleship "Tirpitz", a base on the Atlantic coast. For his actions during this operation he was one of five people awarded the Victoria Cross, the highest award for valour of the British Empire.