26 Jul, 1929
While engaged in firing practice in the Aegean, off the island of Skhiatos, the left gun of "X" turret misfired. The breech operator did not realize it and opened the breech block, causing the charge inside the barrel to explode and also ignite the next one inside the turret; 17 men died in the mishap.
Devonshire returned to England for repairs in August with "the turret swung 'round and the guns awry". As a result of this incident, a new interlock was fitted, which prevented the operator from opening the breech until it had been tripped by the gun firing or manually reset by another operator inside the turret.

23 Nov, 1939
Sinking of the armed merchant cruiser HMS Rawalpindi;

Around midday on 21 November 1939 the German battlecruisers Scharnhorst and Gneisenau, escorted by the light cruisers Köln and Leipzig and the destroyers Z 11 / Bernd von Arnim, Z 12 / Erich Giese and Z 20 / Karl Galster, departed Wilhelmshaven for a raid into the North Atlantic, this was to relieve the pressure of the pocket battleship Admiral Graf Spee operating in the South Atlantic. Late on the 21st the escorts left the battlecruisers.

Just after 1500 hours on 23 November the British armed merchant cruiser HMS Rawalpindi (Capt. E.C. Kennedy, (retired), RN) sighted the Scharnhorst. Rawalpindi was part of the British Northern Patrol and was stationed south-east of Iceland in the Iceland-Faroer gap. Captain Kennedy tried to outrun the German ship and reported to the Admiralty that he sighted the German pocket battleship Deutschland, still believed to be operating in the North Atlantic. Just after 1600 hours, Rawalpindi came within range of the Scharnhorst and was quickly reduced to a flaming wreck. During this engagement Scharnhorst was hit by a 6” shell from Rawalpindi causing only light damage. Scharnhorst and Gneisenau together picked up 27 survivors from Rawalpindi. Rawalpindi finally sank around 2000 hours.

The British light cruiser HMS Newcastle (Capt J. Figgins, RN), that was also part of the Northern Patrol, picked up Rawalpindi’s signal and closed the scene. She sighted the Gneisenau but the Germans managed to escape in the fog.

The Admiralty also thought the ship sighted by Rawalpindi and Newcastle was the Deutschland that was trying to return to Germany. In response to the sighting and destruction of the Rawalpindi the Admiralty took immediate action;
The battleships HMS Nelson (Capt. G.J.A. Miles, RN with Admiral Forbes aboard) HMS Rodney (Capt. F.H.G. Dalrymple-Hamilton, RN) and the heavy cruiser HMS Devonshire (Capt. J.M. Mansfield, DSC, RN) escorted by the destroyers HMS Faulknor (Capt. C.S. Daniel, RN), HMS Fame (Cdr. P.N. Walter, RN), HMS Firedrake (Lt.Cdr. S.H. Norris, RN), HMS Foresight (Lt.Cdr. G.T. Lambert, RN), HMS Forester (Lt.Cdr. E.B. Tancock, RN), HMS Fortune (Cdr. E.A. Gibbs, RN) and HMS Fury (Cdr. G.F. Burghard, RN) departed the Clyde to patrol of Norway to cut of the way to Germany for the Deutschland.

The light cruisers HMS Southampton (Capt. F.W.H. Jeans, CVO, RN), HMS Edinburgh (Capt. F.C. Bradley, RN) and HMS Aurora (Capt. G.B. Middleton, RN) escorted by the destroyers HMS Afridi (Capt. G.H. Creswell, DSC, RN), HMS Gurkha (Cdr. F.R. Parham, RN), HMS Bedouin (Cdr. J.A. McCoy, RN), HMS Kingston (Lt.Cdr. P. Somerville, RN) and HMS Isis (Cdr. J.C. Clouston, RN) departed Rosyth to patrol between the Orkney and Shetland islands.

Light cruiser HMS Sheffield (Capt. E. de F. Renouf, CVO, RN) was sent from Loch Ewe to the last known position of the German ship(s).

On northern patrol, south of the Faroers were the light cruisers HMS Caledon (Capt. C.P. Clark, RN), HMS Cardiff (Capt. P.K. Enright, RN) and HMS Colombo (Capt. R.J.R. Scott, RN). These were joined by HMS Dunedin (Capt. C.E. Lambe, CVO, RN) and HMS Diomede (Capt. E.B.C. Dicken, RN).

Of the ships of the Denmark strait patrol, the heavy cruisers HMS Suffolk (Capt. J.W. Durnford, RN) and HMS Norfolk (Capt. A.G.B. Wilson, MVO, DSO, RN) were ordered to proceed to the Bill Bailey Bank (to the south-west of the Faroers)

The light cruiser HMS Glasgow (Capt. F.H. Pegram, RN) escorted by the destroyers HMS Maori (Cdr. G.N. Brewer, RN) and HMS Zulu (Cdr. J.S. Crawford,RN) were already at sea patrolling north-east of the Shetlands were to be joined by the destroyers HMS Inglefield (Capt. P. Todd, RN), HMS Imperial (Lt.Cdr. C.A.de W. Kitcat, RN), HMS Impulsive (Lt.Cdr. W.S. Thomas, RN) and HMS Imogen (Cdr. E.B.K. Stevens, RN) .

Dispite the British effort to intercept the German ships, both German battlecruisers returned to Wilhelmshaven on the 27th.

13 Sep, 1940
Between 13-25 September 1940 HMS Devonshire (Capt. J.M. Mansfield, DSC, RN) was engaged in Operation "Menace", shelling the coastal batteries and French defeses around Dakar.

23 Jul, 1941
HMS Devonshire (Capt. R.D. Oliver, DSC, RN) sailed from Scapa Flow escorting the carriers Victorious and Furious in a raid against Petsamo and Kirkenes.

2 Nov, 1941
HMS Devonshire (Capt. R.D. Oliver, DSC, RN) was flying the flag of the Senior Officer when an entire Vichy French convoy was captured east of the Cape of Good Hope.

21 Nov, 1941
On the way home after 622 days of patrol, the German raider Atlantis (Capt. Bernard Rogge) met the German submarine U-126 to refuel her north of Ascension Island. During that operation, a lookout reported a warship that turned out to be the British heavy cruiser HMS Devonshire (Capt. R.D. Oliver, DSC, RN) that arrived due to intelligence report on the rendezvous. Devonshire fired from 17000 feet, out of range from german guns. The second and third salvoes hit the German raider, her magazine exploded and Atlantis sank quickly in position 04º12'S, 18º42'W. As U-126 submerged, Dorsetshire made off at high speed, leaving it to the German submarine to pick up the survivors. (see map)

Apr, 1942
HMS Devonshire (Capt. R.D. Oliver, DSC, RN) took part in Operation "Ironclad", the British attack on Madagascar. She did not have a chance to engage since the carrier planes did all the damage.