midget submarine or x craft

Operation Gambit

Operation Gambit was a critical yet often overlooked component of the D-Day landings on June 6, 1944. This mission involved the use of British X-class midget submarines to guide the Allied invasion forces to the Normandy beaches. The bravery and precision of the submariners involved in Operation Gambit ensured the success of one of the most significant military operations in history.

The Objective of Operation Gambit

The primary objective of Operation Gambit was to mark the eastern and western boundaries of the five landing beaches—Utah, Omaha, Gold, Juno, and Sword. This was accomplished using two X-class midget submarines, HMS X20 and HMS X23. These submarines were to position themselves off the coast of Normandy and act as navigational beacons for the incoming invasion fleet.

Preparations and Deployment

Preparation for Operation Gambit began months before D-Day. The X-class midget submarines, originally designed for attacks on enemy battleships, were adapted for this special mission. The submarines were equipped with a range of navigational aids, including sonar and radar reflectors, to ensure they could maintain their positions accurately.

  • HMS X20: Commanded by Lieutenant K.R. Hudspeth, X20 was tasked with marking the eastern flank of Sword Beach.
  • HMS X23: Commanded by Lieutenant George Honour, X23 was responsible for marking the western flank of Juno Beach.

The submarines were towed by larger vessels, known as mother ships, to conserve their limited range and ensure they reached their positions undetected.

Journey Across the Channel

On June 3, 1944, the X-class submarines were towed from their bases in the UK to a point near the French coast. The mother ships released the submarines on June 4, allowing them to navigate the final leg of their journey independently.

Execution of the Mission

On the night of June 4-5, 1944, HMS X20 and HMS X23 reached their designated positions off the Normandy coast. For the next 48 hours, the submarines remained submerged during daylight hours to avoid detection. They surfaced periodically at night to take navigational fixes and ensure they remained in the correct positions.

As dawn broke on June 6, the submarines surfaced and extended their periscopes, which were fitted with lights and radar reflectors. These visual markers were crucial for the navigation of the Allied invasion fleet, helping guide them to the correct landing zones on the heavily defended beaches.

The Significance of Operation Gambit

The successful execution of Operation Gambit had several significant impacts on the D-Day landings:

  1. Accurate Navigation: The periscope markers provided by X20 and X23 ensured that the invasion fleet could navigate accurately. This accuracy was vital for the coordinated landings across the five beaches.
  2. Minimising Casualties: By guiding the invasion fleet to the correct locations, the submarines helped minimise the risk of vessels landing on heavily fortified sections of the coast, thereby reducing potential casualties.
  3. Coordination and Timing: The submarines’ positions were critical for the precise timing and coordination of the landings. The success of the overall operation relied heavily on the fleet arriving at the right place at the right time.


    Operation Gambit exemplifies the bravery and ingenuity of the Royal Navy Submarine Service during World War II. HMS X20 and HMS X23 played a crucial role in the success of the D-Day landings, guiding the invasion fleet with precision and ensuring that one of history’s most significant military operations could proceed as planned. Their contributions, though often overshadowed by the broader scope of D-Day, were indispensable to the Allied victory in Normandy.

    Today, the legacy of many such daring missions lives on, with X24, one of the X-Craft, preserved at the Royal Navy Submarine Museum in Gosport. The museum serves as a reminder of the bravery and innovation of the submarine crews.