Signals Intelligence and the Battle of Jutland
Room 40 in the Admiralty had been producing good intelligence by decrypting intercepted messages since November 1914 but there were two problems: so greatly did the Admiralty prize the Signals Intelligence that it was reluctant to issue it to the Fleet even in a sanitised form in case the Germans learned of its vulnerability. And senior naval commanders, trained in the pre-wireless days where they were masters and commanders of their ships, resented the interference of intelligence with operations. The Signals Intelligence staff knew that the German Fleet would come out into the North Sea on 31 May, but the Commanders at Scapa and Rosyth, Admirals Jellicoe and Beatty were not warned. Why?
There are two versions of what happened:
The first was told by William Clarke, a Room 40 veteran who stayed on after the war and served at Bletchley Park before retiring at the end of WWII. It has been repeated by subsequent historians of the battle and it should be noted that this version was not contradicted by Clarke’s Room 40 contemporaries. The fleet had been correctly warned of the German sortie, but was unnecessarily misled about its timing. This happened because the Director of Operations asked the wrong question of Room 40. He failed to explain what he really wanted to know and thought he knew the significance of what Room 40 told him.
Wishing to know whether the main German Fleet had put to sea, he asked where the callsign of its commander, Admiral Scheer, was currently located. He was told, correctly, that it was in Wilhelmshaven. He then signalled to the British commanders that the German Fleet had not yet left port. In fact it had already done so, as Room 40 knew, leaving Scheer's personal callsign behind — he used the callsign of his flagship when embarked. When the advance group of the British Fleet ran unexpectedly early into the main German Fleet, confidence in the Admiralty's intelligence was shattered, and the Battle of Jutland turned into a missed opportunity. There were other mistakes during the course of the battle, but the first one was probably the most influential.
More recently, Cdr Jason Hines US Navy, has argued that the dissemination system performed as planned, since the Admiralty placed a higher premium on the security of the intelligence source over its operational use by the fleet at sea.
Either way, the story illustrates what happens when the use and protection of Signals Intelligence are not in balance: a problem as real today as it was a hundred years ago.