Upon the outbreak of World War II in 1939, Froggatt intended to join the Royal Navy, but instead joined the Merchant Navy where he trained as a radio operator. He served aboard the freighter "Centaur" when it picked up German survivors of the battle between HMAS "Sydney" and German auxiliary cruiser "Kormoran" in November 1941. Eighteen months later, Froggatt fell ill and was hospitalised in Melbourne. As such, he was not on board "Centaur" when it was torpedoed and sunk by a Japanese submarine.