Why did Hood blow up so quickly in battle?

why did hood blow up so quickly in battle
HMS HOOD on speed trials off the Isle of Arran
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Matthew Wright

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I'm a New Zealand historian with a life-long interest in matters military, particularly naval engineering. My books have principally been published by Penguin Random House. I'm a Fellow of the Royal Historical Society at University College, London.
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When HMS Hood sank in the Denmark Strait on 24 May 1941, the British public reeled. Some 1415 officers and men were lost. It was an appalling human tragedy.

why did hood blow up so quickly in battle
The last known British photo of HMS Hood, 24 May 1941. Note the seas washing over her quarterdeck. Public domain, via Wikipedia.

Hood went down just a few minutes after tackling the German battleship KM Bismarck. What happened? The origins and design of Hood was covered in the previous article – and, as always, complex systems fail in complex ways. The issue that worried the Admiralty was Hood’s deck armour, which was considered inadequate at longer ranges.

Vice-Admiral Lancelot Holland, who led Hood and the battleship Prince of Wales into combat with Bismarck and the heavy cruiser Prinz Eugen in the morning of 24 May 1941, at the south end of the Denmark Strait, was well aware of the official vulnerability of his flagship. This had been given numbers in a 1935 study showing armour penetration at certain angles of fire at specific ranges. He needed to bring Hood quickly through the danger zone – although this meant his squadron could not immediately bring its aft guns to bear.

During the approach, Hood was hit in the midships superstructure and set afire, ‘cooking off’ ready-use 4-inch gun and 7-inch ‘unrotated projectile’ (rocket) anti-aircraft munitions around her boat deck. Then, at 0559 hours on 24 May 1941, as the range dropped to around 18,200 yards, Holland ordered a turn of 20 degrees to bring all guns to bear. A few seconds later, observers saw a pillar of fire erupt around Hood’s main-mast, swiftly engulfed by a larger explosion around X-turret. Hood began rolling to port and sinking by the stern, her bows rising almost vertically as she went down. Just three survived out of 1,418 officers and men on board.

What generally happened was clear; Hood had suffered a massive internal explosion, flooded quickly aft – an area with low reserve buoyancy – suffered catastrophic structural failure, and sank in just three minutes.

However, determining exactly what happened was challenging. A Board of Enquiry, convened under Vice-Admiral Sir Geoffrey Blake on 2 June 1941, concluded that a shell from Bismarck penetrated Hood’s armour and detonated a 4-inch magazine, collapsing the bulkhead separating it from the 15-inch magazine of X-turret, which also detonated – possibly triggering Y-magazine.

Exactly how the magazines were hit was debated, but the consensus was that a German shell penetrated the upper deck, likely aft of the after engine room where a proposed addition of 3-inch armour had been declined because of weight. It was not conclusive; there were other possible trajectories. Admiral Sir John Tovey, Commander in Chief of the Home Fleet, was concerned by the possibility of a short-falling shell penetrating below the belt armour in heavy seas, when the wave profile altered the depth of water over the lower hull. Bismarck hit Prince of Wales in precisely this way during the battle; fortunately the shell never exploded.

The Board’s conclusions did not satisfy the Director of Naval Construction, Sir Stanley Goodall, who suggested the pillar of flame around the mainmast was the midships torpedo warheads blowing up – detonated by a shell or the boat deck fire – which then broke the ship’s back. The Controller of the Navy, Vice-Admiral Bruce Fraser, objected; experience showed that one torpedo exploding in its mantlet did not detonate others stored nearby. But a second Board was called. This convened on 27 August 1941 under a former commander of Hood, Rear-Admiral H.T.C. Walker.

why did hood blow up so quickly in battle
A still from a film by Paul Smalenbach, on board Prinz Eugen, of Hood sinking. Public domain, via Wikipedia.

This second Board went into massively greater detail but drew the same conclusions as the first, adding that the blast near the mainmast was likely the result of the 4-inch magazine deflagration explosion venting through the engine room ducts. The second Board also discounted the underwater shell theory and showed that the boat-deck fire could not have detonated the 4-inch magazine providing the supply trunks were closed. And they discounted a munitions handling accident.

Debate continued in historical studies and among enthusiasts.  Then, in 2001, the wreck was found by Blue Water Recoveries and a technical study made by William Jurens, William Garzke, Robert O. Dulin, John Roberts and Richard Fiske. Their conclusions endorsed both the Board findings of 1941; the 4-inch magazine had set off X- and probably Y-turret magazines.  But there was an ironic kicker. The Admiralty of the day had been worried by the vulnerability of Hood‘s decks – which, as we have seen, was why Vice-Admiral Holland closed in fast. However, the authors of the new study noted that Bismarck’s incoming shells were falling at 12-14 degrees at a target angle of 53 degrees. The implication is that the side armour, not the deck, was penetrated – which was possible as Hood began to heel under the turn, reducing the effective angle of the sloped armour (shown in the diagram in the previous article).

Irrespective of the shell pathway, it isn’t surprising that the official analyses of 1941 came up with a plausible cause – ‘chain’ detonation of magazines. Both Boards included professional officers, including a former commander. Their expertise reflected the point that an engineering study of how ships performed was part of the deal for seagoing officers.

At the end of the day, much of this debate is immaterial: the fact remains that Hood blew up and sank – and 1,415 men died. It was a human tragedy. While this figure was subject to some debate through slight uncertainties over how many were embarked on that last sortie, 1415 has been shown to be correct.

It is to the memory of these brave souls, and to their families – who had to endure the loss of their loved ones – that our thoughts must go when we consider the loss of HMS Hood.

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Copyright © Matthew Wright 2017


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