During World War II, Operation Diplomat was an Allied naval training operation. It was executed in March 1944 by the British Eastern Fleet to practice operational procedures that would be used by ships allocated to the British Pacific Fleet. The ships from the Eastern Fleet were HMS Renown (flagship of Vice-Admiral second-in-command Eastern Fleet), HMS Queen Elizabeth and HMS Valiant, the fleet carrier HMS Illustrious, cruisers HMS London, HMS Cumberland, HMNZS Gambia and HMS Ceylon, and ten destroyers.