the disposition of the German forces, and then their movement orders for the attack on the Low Countries prior to the Battle of France in May. An Ultra decrypt of June 1940 read KNICKEBEIN KLEVE IST AUF PUNKT 53 GRAD 24 MINUTEN NORD UND EIN GRAD WEST EINGERICHTET ("The Cleves Knickebein is directed at position 53 degrees 24 minutes north and 1 degree west"). This was the definitive piece of evidence that Dr R V Jones of scientific intelligence in the Air Ministry needed to show that the Germans were developing a radio guidance system for their bombers. Ultra intelligence then continued to play a vital role in the so-called Battle of the Beams. During the Battle of Britain, Air Chief Marshal Sir Hugh Dowding, Commander-in-Chief of RAF Fighter Command, had a teleprinter link from Bletchley Park to his headquarters at RAF Bentley Priory, for Ultra reports. Ultra intelligence kept him informed of German strategy, and of the strength and location of various Luftwaffe units, and often provided advance warning of bombing raids (but not of their specific targets). These contributed to the British success. Dowding was bitterly and sometimes unfairly criticized by others who did not see Ultra, but he did not disclose his source. Decryption of traffic from Luftwaffe radio networks provided a great deal of indirect intelligence about the Germans' planned Operation Sea Lion to invade England in 1940. On 17 September 1940 an Ultra message reported that equipment at German airfields in Belgium for loading planes with paratroops and their gear, was to be dismantled. This was taken as a clear signal that Sea Lion had been cancelled. Ultra revealed that a major German air raid was planned for the night of 14 November 1940, and indicated three possible targets, including London and Coventry. However, the specific target was not determined until late on the afternoon of 14 November, by detection of the German radio guidance signals. Unfortunately, countermeasures failed to prevent the devastating Coventry Blitz. F. W. Winterbotham claimed that Churchill had advance warning, but intentionally did nothing about the raid, to safeguard Ultra. This claim has been comprehensively refuted by R V Jones, Sir David Hunt, Ralph Bennett and Peter Calvocoressi. Ultra warned of a raid but did not reveal the target. Churchill, who had been en route to Ditchley Park, was told that London might be bombed and returned to 10 Downing Street