Clyde commissioned in 1935 and the outbreak of the Second World War found her in the Mediterranean Sea with the 1st Submarine Flotilla stationed at Malta.

[1] On 13 May 1940, while on patrol in Scandinavian waters on the surface, Clyde met the German auxiliary cruiser Widder, resulting in an exchange of gunfire which lasted for over an hour, with no hits for either side.

[3] In September 1941, she unsuccessfully attacked three German submarines U-67, U-68 and U-111 during an action in Tarrafal Bay, Cape Verde Islands,[1] although she accidentally collided with U-67 when she dived, leaving the latter vessel badly damaged and obliged to return to base.

[1] In March 1945, she recorded another string of kills against the Japanese, sinking two sailing vessels and the auxiliary submarine chaser Kiku Maru.

[6] In May 1945, having completed 36 operational patrols and with a final war total of 6 enemy vessels sunk, Clyde was moved to Mombasa for repairs.