Nigeria served in Home waters and off the Scandinavian coast for the early part of the war. On 28 June 1941 Nigeria, in company with the destroyers, and intercepted the in thick fog north-east of Jan Mayen Island. The German ship was detected through the use of HF/DF. The crew of Lauenburgabandoned ship after they were fired upon, allowing the British to board her. Valuable codebooks and parts of the Enigma machine were found aboard and recovered. This was one of the earliest captures of Enigma material of the war, and came a few weeks after the destroyer had captured the first complete Enigma machine from the German submarine on 9 May 1941. In July 1941, Nigeria became the flagship of Force K, commanded by Rear AdmiralPhilip Vian. During this period, Force K made two expeditions to Spitsbergen, the first to ascertain the situation and the second, in September, to escort a troopship,, with Canadian troops and a team of demolition experts. Their task was to evacuate Norwegian and Soviet personnel from the archipelago and destroy coalmines and fuel stocks that might be of use to the enemy. Bear Island was also visited to destroy a German weather station. The two cruisers of the task force, Nigeria and diverted to intercept a German convoy. During this action, Nigeria sank the German training ship, but suffered serious damage to her bow, possibly having detonated a mine. On return to Britain, she was sent to Newcastle for repairs.
Nigeria was then assigned to operate in the Mediterranean. On 12 August 1942 she was participating in Operation Pedestal, escorting a convoy bound for Malta. She was the flagship of the close escort group, commanded by Admiral Harold Burrough. Nigeria was torpedoed and damaged by the but managed to make it back to Gibraltar escorted by three destroyers. 52 crew were killed in the attack. Admiral Burrough meanwhile transferred his flag to the destroyer whilst Nigeria returned to Gibraltar. She was sent from there to the United States for repairs, which took nine months to complete. After these were complete, she operated off the South African coast, and on 12 March 1943 she picked up 30 survivors from the American merchant that was torpedoed and sunk on 8 March 1943 by the about north-east of Durban. Nigeria was then assigned to operate with the Eastern Fleet from February 1944 until December 1945, when she returned to the UK to be refitted. During her time in the far east, she participated in raids on Sumatra.
Post war
Nigeria survived the war and continued in service with the Royal Navy, as the only Colony-class cruiser, maintaining four triple 6-inch turrets, 'X' turret finally being removed in 1954. In 1954 it was sold to India and went under reconstruction, largely on the pattern of the rebuild of HMS Newfoundland, possibly incorporating some of the electronics and radar intended by the RAN to be used on the refit of HMAS Hobart, which was abandoned. On 29 August 1957 when she recommissioned into the Indian Navy, who renamed her Mysore. During her time with the Indian Navy, she collided with the destroyer, severely damaging Hogues bow. Mysore was in service with them for a further 28 years until she was decommissioned on 20 August 1985.
