By the beginning of June, thanks to the code-breaker ‘Ultra’, which since mid-1940 had enabled the decrypting of German military intelligence cyphers, the British cabinet was aware that Hitler would strike against the Soviet Union during the second half of the month.226 The British had also been tipped off, indirectly, through a leak passed on via Dahlems, by no less a person than Göring — concerned, as Heß was, to avoid a two-front war.227 Anxious to wean the Soviet Union away from Germany, Churchill was among a number of those who had let Stalin know as early as April to expect a German attack.228
The aim of Eden, Cadogan, and Lord Beaverbrook was now to exploit Heß’s capture by sowing further doubts in Stalin’s mind about whether Britain was about to strike a deal with Hitler, based upon peace proposals advanced by the former Deputy Führer, while at the same time, through warnings of German intentions, leaving the door open to a
Predictably, Stalin indeed followed the third option. He brushed away warnings, confident that Hitler would not risk a two-front war. Heß’s defection bolstered this confidence, since Stalin presumed the Deputy Führer had been commissioned by Hitler to put out peace feelers, and that only a few weeks remained available if an attack were to be launched. The silence from London about Heß together with rumours that Britain might be ready to pull out of the war, aligned with the warnings of an imminent attack by Hitler on Russia, further reinforced the presumption of a serious split within the British government. From Stalin’s point of view, this meant the likelihood of delay, thereby hindering agreement with Germany, and blocking the chances of a German attack while there was still time that year.230
However, Stalin tried to keep his options open — just in case. On the day that the capture of Heß was announced in London, 13 May, Stalin had four additional armies moved into the western border area of the Soviet Union. A further twenty-five divisions followed early in June, when rumours of Berlin and London agreeing a separate peace were rife.231 By the time ‘Barbarossa’ came to be launched, large Russian tank divisions were ranged in forward positions in an arc around Bialystok and Lemberg. They were intended to be in a position to convert readily into an attack-force should, against Stalin’s expectations, a separate peace be speedily agreed between Britain and Germany.232
Stalin had seen in Heß’s flight to Britain a rationality, as part of Hitler’s planned strategy, which was not there. He had been encouraged in this by British policy. What the Soviet dictator could not contemplate was, unfortunately for him and his country, the real position: that Hitler had had nothing to do with the absurd Heß adventure; that he had no desire at this point to enter into negotiations with Britain; and that he was fixated upon a ‘war of annihilation’ to destroy the Soviet Union, aimed at leaving Britain then with no choice but to seek terms.
By the middle of May, after a week preoccupied by the Heß affair, Hitler could begin to turn his attention back to this imminent showdown. The directive he signed on 23 May, supporting the pro-Axis regime in Iraq (which had come to power following a military coup at the beginning of April, had refused to allow British troop movements in the country, and had sent Iraqi troops to surround a British air-base) had little more than nominal significance. A small number of German aeroplanes, carrying troops, had already flown to Iraq in mid-May. They could do little to help the weak Iraqi army fend off the invading British relief forces, which ultimately re-established a pro-British administration. In any case, Hitler’s directive made plain that a decision on any German attempt to undermine the British position in the eastern Mediterranean and the Persian Gulf would only follow ‘Barbarossa’.233
