When the Second World War began in September 1939, Effingham was assigned to the Northern Patrol, but severe engine problems caused her to spend most of the next six months under repair.

In between dockyard visits, the ship ferried a load of gold bullion to Canada and was briefly assigned to the North America and West Indies Station.

The Hawkins-class cruisers were designed to be able to hunt down commerce raiders in the open ocean, for which they needed a heavy armament, high speed and long range.

[5] The ships were originally designed with 60,000-shaft-horsepower (45,000 kW) propulsion machinery, but the Admiralty decided in 1917 to replace their four coal-fired boilers with more powerful oil-burning ones.

[6] Effingham carried 2,186 long tons (2,221 t) of fuel oil to give her a range of 5,640 nautical miles (10,450 km; 6,490 mi) at 10 knots (19 km/h; 12 mph).

It used data provided by the 15-foot (4.6 m) coincidence rangefinder in the gunnery director positioned under the spotting top at the head of the tripod mast.

Provision was made for one Mk III* High-Angle Control System (HACS) on the spotting top roof and another amidships, although they were not installed until a refit in mid-1939.

Provision was also made for a pair of octuple mounts for two-pounder Mk VIII "pom-poms" and their directors, but they were not installed until another refit in early 1940.

[21] The ship was laid down by HM Dockyard, Portsmouth, on 6 April 1917, launched on 8 June 1921 and completed in July 1925,[9] with Captain Cecil Reyne in command.

Representatives from Effingham attended the coronation of the Emperor of Ethiopia, Haile Selassie, on 2 November 1930 and her Royal Marine band provided entertainment during the affair.

On 14 June 1932 the ship briefly became the flagship of Rear-Admiral Martin Dunbar-Nasmith, Commander-in-Chief of the East Indies Station, but he hauled his flag down on 1 October and the cruiser rejoined the 4th LCS.

[18] Effingham recommissioned on 15 June 1938 with Captain Bernard Warburton-Lee in command and became the flagship of Vice-Admiral Max Horton, Commander-in-Chief, Reserve Fleet.

At some point during the year before August, the ship received her missing HACS directors and exchanged her single four-inch guns for new twin-gun mounts.

On 9 August she hosted King George VI as he met the captains of sixty ships during his review of the recommissioned Reserve Fleet in Weymouth Bay.

[24] After the British declared war on Germany on 3 September, the Northern Patrol's tasks expanded to include intercepting any German commerce raiders attempting to breakout into the Atlantic.

The report was false, but the ships remained off the entrance to the Romsdalsfjord on 17–18 April as the British began landing troops at Molde and Åndalsnes, further inside the fjord.

On the 20th, Admiral of the Fleet Lord Cork, the newly appointed supreme commander of Allied forces in Norway, hoisted his flag aboard the cruiser.

[27] As soon as the 2nd Battalion, the South Wales Borderers could be transferred from Ankenes to Harstad, Auchinleck decided to send them and the headquarters of the 24th Guards Brigade to reinforce the defences of Bodø.

As the ships approached Bodø, Howson suggested that the threat of submarine attack was higher in the main channel and that the squadron could use a narrow strait between the island of Bliksvær and the Terra Archipelago instead.

As the squadron was entering the entrance to the strait around 19:47, the destroyer touched a submerged rock of the Faxsen Shoal, tearing off her port propeller and its bracket, but not further damaging the ship.

Although the ship was settling on an even keel, Howson was concerned that she might capsize with the loss of most of her crew and passengers and ordered Echo to tow Effingham to shallow water to allow her to be beached around 20:15.

[30] Echo was left behind and Howson went aboard her to supervise the attempt to salvage material by the small ships from Bodø and to ensure that Effingham was thoroughly wrecked.