Instead, when the big Soviet offensive — Operation Bagration — did take place a fortnight or so later, it involved a series of powerful attacks against four different German Army Groups along different sections of the long Eastern Front. Certainly, Bagration was itself devastating. As Army Group Centre crumbled, the German army lost more than a million men within 150 days and the Red Army pushed deep into Poland. Bagration was, even so, not the death-blow that the alternative offensive strategy might have brought. Despite the heavy losses, the Eastern Front did not totally collapse. Field-Marshal Walter Model was able to call upon last reserves of panzer troops to block the advance on Warsaw for several weeks, and to stabilise — for the time being — the tottering front. Probably, the Soviet military leadership had, in the light of earlier examples where the Germans had surprised the Red Army by the extent and force of their defence and imposed significant losses, overestimated the resilience of the Wehrmacht at this time. It has also been surmised that Stalin's own experience of the Red Army's defeat by the Poles near Warsaw in 1920, for which he had some personal responsibility, might have played a part in the decision not to risk a repeat disaster on the Vistula, this time at the hands of the Germans, by undertaking the big attack through Kovel. Whatever the reason, the chance to end the war early came and went.

Had the offensive been successfully undertaken, and had Berlin fallen (as seemed a likely consequence), the war would have been close to being over. Hitler's suicide would surely have taken place in June or early July 1944, since, as was in reality the case nearly a year later, he would not have allowed himself to be captured alive. German defences not just in the east might well have collapsed since any successor as leader, whether drawn from the military or from the ranks of leading Nazis, would have had little choice but to sue for peace. By then, the Russians would probably have pressed to a line far to the west of where the eventual east-west division was fixed. The Western Allies might well have been able to break out of Normandy earlier, as, presumably, German troops from the Western Front were rushed eastwards. But, most likely, they would not have made anything like the territorial gains that in reality they did go on to make. Wherever the Iron Curtain eventually fell, it would have been in western, not eastern, Europe. Soviet dominance of the continent would have been more likely. This would hardly have been welcomed by the Western Allies. So possibly, a "hot", not "cold" war between West and East would have ensued, with a distinct chance that the first atom bomb would have fallen not on Hiroshima, but on Moscow.

A final chance to end the war in 1944 was lost through miscalculation on the part of the Western Allies. By mid-August 1944 the Germans seemed in the eyes of  Western Allied leaders to be heading for imminent defeat. The German army had lost over 200,000 men in western Europe during August following the Allied break-out from Normandy. Morale in the Wehrmacht was extremely low at this point as retreat looked like turning into a rout. Paris fell without a fight on August 25, Brussels was liberated on September 3 and Antwerp captured with its vital harbour undestroyed next day. The Allies were jubilant. The end was in sight. Or so it seemed. From this point onwards, the offensive stalled. The initiative was lost, and not fully regained until the following March. A significant factor was the difficult relationship at the top of the Allied military leadership between the supreme commander, General Dwight D. Eisenhower, and the British Commander Field-Marshal Bernard Montgomery. Eisenhower's strategy was to advance on the Reich borders on a broad front before German defences could be consolidated. Since the Allies had by this time some two million men on the Continent, with many more on the way and with almost complete air supremacy, it was a feasible prospect-though much could go wrong. However, Montgomery, keen to press into the Ruhr-Germany's industrial heartland  — and on to Berlin, insisted on an operation to seize the Rhine crossings in the Netherlands. Eisenhower, to the dismay of some of his generals, concurred in according priority to Montgomery's strategy. However, once the attempt to capture the bridge at Arnhem through airborne assault had proved disastrous, amid high British losses, and given that the Scheldt estuary near Antwerp had not been secured, allowing large numbers of German troops to retreat to safety, Allied hopes of a rapid end to the war had evaporated.

Had Eisenhower's original strategy been followed through, there might have been the chance of a German military collapse across much of the Western Front. A rapid advance through the Reich's western provinces and into northern and central parts of Germany, including a push on Berlin, could have been feasible. Presumably, the German leadership would have had to transfer forces from the east to try to hold the crumbling Western Front, opening up the way for the Red Army to enter the Reich from the east far earlier than January 1945, as turned out to be the case. Where the lines would have congealed by the time that Germany capitulated — Hitler having at some point committed suicide — is anybody's guess. Conceivably, however, more of Germany would have fallen to the Western powers than in reality transpired, and before any final agreement with the Soviet Union on the division of Germany had been reached. Depending upon the date of surrender, the Reich might have survived with truncated borders-and the scope for future border revision problems. With most if not all of Germany dominated by the Western powers, the scope for tension with the Soviet Union following the end of hostilities would have been increased. Probably, however, a form of Control Commission, such as did in fact take over, would have run Germany, following a deal with the Soviet Union. Politically, the outcome might have ultimately resembled what did come to pass-though without the immense losses that accompanied the terrible last phase of the war.

In each of the three speculative scenarios sketched above, human agency — Stauffenberg's inability to prime the second bomb, the Soviet military's leadership misjudgment of German army strength in the east, the decision to risk the landing at Arnhem — had played its part. But the human misjudgment was in each case conditioned by other factors-the organisational difficulties of the German Resistance, the risk aversion of the Soviet leadership because of earlier costly experience, the difficulties of unifying American and British war strategy. E.H. Carr's parable used to illustrate historical causation has its echo in the examples used above. History followed no inevitable course. But what eventually transpired was far more than simple chance.