The Battle of Jutland, off the coast of Denmark, was the largest naval battle of the First World War between the British Royal Navy Grand Fleet and the German Navy’s High Seas Fleet, on the 31st May and 1st June 1916. It was not the decisive engagement that both sides had hoped for, the Germans destroyed more British ships than they lost but were still contained in their harbours. This allowed the British to focus on anti-submarine action elsewhere but the battle had failed to remove the threat posed by the German Navy and had also dented the reputation of the Royal Navy. The disputed outcome of the Battle of Jutland is surprising, considering the information available to the British through military intelligence, so what went wrong?

The British Admiralty’s cryptanalysis department during the First World War was known as Room 40. They were incredibly successful in their role, decrypting around 15,000 German messages throughout the war. Their success was partially due to captured codebooks but also due to the Germans sending routine messages as well as the Germans transmitting at full power, allowing the British to intercept and understand them more easily. Some of the more valuable decryptions for the Royal Navy were the positions of the German fleet, so they could respond accordingly to any new movements such as what occurred in January 1915, where Room 40 identified a German raiding squadron heading for Dogger Bank in the North Sea, allowing the Royal Navy to prepare and engage them, sinking the German armoured cruiser Blücher.

Despite the large wealth of information available to Room 40, not all of it was utilised effectively. The Admiralty saw it as their priority to ensure the existence of the codebreakers and the intelligence they gathered remained a secret from their German foes, otherwise they feared they may change code and access to information would be lost. As a result, very little information was communicated outside of Room 40; what did leave had to be approved by Rear-Admiral Henry Oliver, Director of Naval Intelligence. This focus on protecting the secrecy of the abilities of Room 40, contributed to the indecisiveness of the Battle of Jutland.

On the 30th May, a signal was intercepted from the German High Seas Fleet commander, Vice-Admiral Reinhard Scheer, referencing the following day, making it clear to the British that action was imminent but unclear about the scale. The British fleet commander Admiral Sir John Jellicoe, not fully knowing the German objectives, positioned his fleet to stop enemy movement into the Northern Atlantic or Baltic. He was due to rendezvous with Vice-Admiral Sir David Beatty’s squadrons but ran into the scouting group of the German fleet and engaged in battle, being lured towards the main German fleet exactly as Scheer had planned.

However, Jellicoe had been unintentionally misled about the size of the German forces at sea which led him to believe that the main battle section of the High Seas Fleet was still in port at Wilhelmshaven. This came about from the Director of Operations asking Room 40 where the callsign DK, the one used by Admiral Scheer, was currently located. Intelligence responded it was still in harbour, even though they were aware Scheer used a different callsign when at sea but because Room 40 was not told the reason for this information request, to locate the High Seas Fleet, they did not inform the Director, who in turn informed Jellicoe, that Scheer was still in port.

This mismanagement of military intelligence would leave the commanders in the battle without the full picture. If Jellicoe had known he would be engaging the full German fleet perhaps he could have made different decisions and the battle would have resulted in a British victory rather than the indecisive stalemate. There were other mistakes made during the battle that led to this conclusion but arguably the failure in communication between Room 40 and the commanders is one of the most important. It would not be until the revelation of the Zimmerman telegram the following year that confidence in Room 40 and Naval Intelligence was restored.

By Daniel Smith