She had the unfortunate experience of sinking two Allied ships during her wartime service, once through accidental collision and the other by gunfire after a case of mistaken identity.

[1] She entered service without some components of her main armament's fire control system, which were subsequently fitted at the end of that year.

[1] Glasgow remained allocated to the Home Fleet during the first year of the Second World War, under the command of Captain Frank Pegram from July 1939 to April 1940.

With war approaching, Glasgow sailed on 2 September 1939 from Grimsby to patrol off the Norwegian coast with Humber Force to intercept any German commerce raider attempting to reach the Atlantic or any blockade runner returning to Germany.

While operating with the Humber Force she in company with the cruisers Southampton and Edinburgh was subjected to a heavy air attack by the Luftwaffe on 9 October 1939, but suffered no damage despite 120 bombs being dropped on the ships.

On 29 April, she evacuated King Haakon and Crown Prince Olav of Norway, Nygaardsvold's Cabinet and part of the Norwegian gold reserves when they fled from Molde to Tromsø, escaping the advancing German forces.

[6] Whilst operating in home waters after the withdrawal from Norway, Glasgow accidentally rammed and sank the destroyer HMS Imogen in thick fog off Duncansby Head on 16 July 1940.

[1] Following repairs Glasgow was transferred to the Mediterranean where she was employed as a convoy escort and as a reinforcement of the 3rd Cruiser Squadron based at Alexandria.

As a result of her diminished capability Glasgow was allocated to the Indian Ocean, leaving Alexandria on 12 February 1941 and passing through the Suez Canal.

On 22 January, Admiral Scheer was sighted by the spotter aircraft from Glasgow, the East Indies Task Force was deployed to the reported area.

At midnight on 9 December 1941, Glasgow sank the RIN patrol vessel HMIS Prabhavati with two lighters in tow en route to Karachi, with 6-inch shells at 6,000 yards (5,500 m).

As well as repairing the damage from her 1940 torpedo attack, additional 20 mm Oerlikon cannons were added to improve her close range anti-aircraft capability.

In March she intercepted the German blockade runner Regensburg in the Denmark Strait as it returned from the Far East with valuable rubber, tungsten and other commodities.

Between August and September she entered the HM Dockyard at Devonport where her aircraft facilities were removed and more 20 mm weapons were installed to improve her air defences.

With the demand for cruisers in the European theatre decreasing it was decided to withdraw Glasgow and modernise her in preparation for the ongoing war in the Pacific.

Entering a shipyard on the River Tyne on 3 July 1944 her aft 6-inch turret ('X') was removed to compensate for the additional weight of adding the more powerful anti-aircraft armament needed to counter the threat of kamikaze attacks.

She transferred to the Indian Ocean arriving in Colombo on 5 October to relieve HMS Phoebe as the flagship of 5th Cruiser Squadron.

Following a refit she was re-commissioned in September 1948 and on 26 October, 1948, Glasgow replaced HMS Sheffield at her new base, the Royal Naval Dockyard in the Imperial fortress colony of Bermuda, as the flagship on the America and West Indies Station.

[12] In 1955 Glasgow returned to the UK, and in May 1955 onwards rejoined the Home Fleet as flagship of the Flag Officer D (Flotillas) before being paid off at Portsmouth in November 1956.