Tovey was under strict orders to steer clear of the German airfields in northern Norway, where the Luftwaffe had massed 103 bombers, 42 torpedo-bombers, 20 dive-bombers, and 89 reconnaissance aircraft to block any convoy's passage. The Germans also had 10 U-boats on station, so their tactical reconnaissance advantage was formidable. The Allies hoped to trump this with strategic intelligence gleaned through ultra decrypts; however, a change in German Enigma cipher settings on 3 July led to an intelligence blackout. Political pressure from Washington and Moscow compelled leaders to insist that the convoy proceed, and it sailed blindly into a German trap.
The British first sea lord, Admiral of the Fleet Sir Dudley Pound, agonized over the choices of action available to him. He could not recall the convoy, and he would not allow the Home Fleet to close with it and risk an overwhelming German air and submarine attack. Allied intelligence also assumed that German navy surface units in Norway would attempt an attack. These forces consisted of the battleship Tirpitz, the pocket battleships Scheer and Lützow, the heavy cruiser Hipper, 10 fleet destroyers, and 2 oceangoing torpedo boats.
Even before PQ 17 sailed, Pound informed Tovey that if he believed a German surface attack was imminent, he would order the convoy to scatter. Tovey pointed out in no uncertain terms to Pound that this was contrary to all recent British experience. In any case, at 9:00 p.m. on 4 July, Pound, incorrectly assuming that the Germans' big ships were on their way to intercept the convoy and would reach it early the next day, began sending signals ordering PQ 17 to scatter and its cruisers and fleet destroyers to withdraw toward the Home Fleet, as they were too weak to face the German squadron that he believed to be at sea. Although scattering was the logical precaution when a convoy was under surface attack, it was a suicidal move when made against aircraft and submarines.
Of the 34 merchant ships still with the convoy when the order to scatter was given, only 13 reached Murmansk. The Allies had suffered one of their worst maritime defeats of the war, the tragedy of which was deepened by the fact that it need not have happened. Convoys to Murmansk were then suspended for the summer, as perpetual Arctic daylight and German strength made them untenable.
Kemp, Peter. Convoy! Drama in Arctic Waters. London: Arms and Armour Press, 1993.; Roskill, S. W. White Ensign: The British Navy at Way, 1939–1945. Annapolis, MD: Naval Institute Press, 1960.; Woodman, Richard. Arctic Convoys. London: John Murray.