The refits lasted throughout October, and on completion of the final harbour trials on 1 November 1940 she was nominated to join the 17th Flotilla operating in the Western Approaches.

[1] The next day, while carrying out sea trials she collided with SS Risoy and sustained damage,[6] but continued and arrived safely at Liverpool, where she underwent repairs from 7 to 24 November.

She spent September working up with her Royal Navy crew and rejoined the group in October, where she covered convoys between Britain and West Africa.

[1] On 15 September she picked up the survivors of the Norwegian motor tanker Vinga, which had been damaged in an enemy air attack.

[13][14] If this drydock could be put out of action, any offensive sortie by Tirpitz into the Atlantic would be much more dangerous for the Kriegsmarine to carry out, making it less likely that they would risk deploying her.

Accompanying her would be 18 small boats carrying British Commandos,[16] who would destroy the dock's pumping and winding machinery and other infrastructure.

A 12-pounder gun was installed forward and eight 20 mm (0.79 in) Oerlikon anti-aircraft cannon were mounted on the upper deck.

Some extra armour was provided to protect the bridge structure, and unnecessary stores and equipment were removed to lighten the destroyer.

[18][17] Campbeltown steamed from Devonport to Falmouth, Cornwall on 25 March to join the other ships that would take part in the operation.

The preliminary air raid carried out through heavy cloud by 35 Armstrong Whitworth Whitleys and 25 Vickers Wellingtons was much smaller than originally planned and was ineffective, merely alerting the defenders of something unusual happening.

Nevertheless, by flashing genuine German recognition signals, the force, with Campbeltown flying the flag of the Kriegsmarine, approached to within less than 1 mi (1.6 km) of the harbour before being fired upon.

During the final approach, the crew of Campbeltown lowered the emblem of the Kriegsmarine and hoisted the battle ensign of the Royal Navy.

The Commandos and ship's crew came ashore under heavy German fire and set about demolishing the dock machinery.

[17] The ship's bell of HMS Campbeltown was given to the town of Campbelltown, Pennsylvania, as a gesture of appreciation towards the United States for the Destroyers for Bases Agreement program.