Gloucester was detailed several times during the war to search for German commerce raiders, but her only success was the capture of one supply ship in early 1915.

The Bristol sub-class[Note 1] were rated as second-class cruisers suitable for a variety of roles including both trade protection and duties with the fleet.

[5] This armament was considered rather too light for ships of this size by the Royal Navy,[6] while the waist guns were subject to immersion in a high sea, making them difficult to work.

[2] As tensions rose with Germany in the first few days of August 1914, before Britain declared war, Gloucester was deployed at the mouth of the Adriatic Sea, together with the bulk of the Mediterranean Fleet, by its commander, Admiral Sir Archibald Berkeley Milne.

But Britain and Germany were not yet at war so Milne turned to shadow the Germans as they headed back to Messina, Sicily, to recoal.

Therefore, Milne stationed the battlecruisers Inflexible and Indefatigable at the northwestern exit of the Strait of Messina as he still expected the Germans to break out to the west where they could attack French troop transports.

Rear Admiral Wilhelm Souchon ordered Breslau to turn about and pretend to lay mines in an effort to scare off Gloucester.

This caused Souchon to turn and open fire on the British cruiser and Kelly disengaged, having accomplished his goal.

Kelly was forced to break off his pursuit at 16:40 as Milne had strictly forbidden him to pass Cape Matapan, Greece, and his coal was running low.

[13] In November the ship was ordered into the Indian Ocean to search for German commerce raiders, although she was recalled shortly afterwards to rejoin the 2nd LCS of the Grand Fleet in home waters.

As Beatty turned east to rendezvous with them, Gloucester was unable to reach the head of the Grand Fleet's line and was forced to steer for the unengaged side to avoid fouling the range with her funnel smoke.

[20] By 20:10, Beatty's ships were in front of the Grand Fleet and the 3rd LCS was screening them when the flagship, Falmouth, spotted five cruisers of the 4th Scouting Group and the squadron closed to engage at full speed.

[23] Gloucester was detached to the Indian Ocean in March 1917 to search for the German commerce raider SMS Wolf, but was recalled on 23 May.