As we mark the 70th anniversary of the start of the Second World War, the British obsession with the war runs on and on. There is the endless recycling of the same themes - Dunkirk, the D-day landings and Churchillian greatness - that starts to devalue the heroism of those times as much as to celebrate it. There is the nostalgia, pride and self-congratulation that now do more to block than to illuminate any real appreciation of how the war changed the world and Britain's place in it.

The British's finest hour? To be sure, it was good that Britain finally took a stand against fascism. But going to war with Germany in 1939 did not prevent Poland's disappearance. Nor could the combined forces of Britain and France prevent most of western Europe being overrun the following year. Many had expected a German attack on France to produce a replay of the First World War's western front stalemate. Everyone was shocked by the terrifying rapidity of the German advance and the awesome might of the Wehrmacht. Avoiding total defeat - as at Dunkirk - and invasion - thanks to the Battle of Britain - were the closest the British could come to victory on their own. British strategists were left fearful of the German army and convinced that any attempt in the short term on the Nazi empire would simply lead to another British humiliation.

As a result, the British fought off American and Soviet demands to launch a second front as long as they could. Churchill was all too aware of the inadequate military forces at his disposal, their inadequacy masked only by the extraordinary good fortune that came to the British when the Germans invaded the Soviet Union and the Japanese declared war on the US. Had neither of these events occurred - and it is revealing that both left Churchill jubilant - it is hard to see how Britain could ever have dislodged the Nazis from Europe.

The British supplied arms to guerrillas and partisans hoping they would rise up and drive the Germans out of their homelands; but militarily most of them had no real impact on the war hit and run was the most they could hope for, along with the murderous German attacks on innocent villagers that they brought in their train. Regular armies were the decisive factor throughout, and for much of the war in Europe the Wehrmacht had the edge.

When the tide turned, it turned in the east. D-day, when it finally came, was scarcely the overwhelmingly decisive event one would imagine from the last few years' barrage of publications. How many people have even heard of Operation Bagration, the simultaneous Soviet offensive through Belorussia, that engaged almost 10 times the number of German divisions, and destroyed three Wehrmacht armies? Very few, I suspect - it failed to garner any attention during the D-day celebrations. Yet Bagration, the biggest and most successful surprise attack in history, dwarfed what was happening in Normandy. As the Soviets stormed west of their prewar boundaries for the first time, this was confirmation that it was the Red Army that really won the war against nazism, and the moment Stalin began to think seriously about how to rule eastern Europe.

In hindsight, perhaps what is most revealing is how much Britain depended throughout the war on its colonies. If the Russians saved us in Europe, the empire was indispensable for shoring up British power outside it. Dominion units played a critical role in the Mediterranean, despite fears of the Japanese back home. As for the two-million-strong Indian army, its units operated almost everywhere as well as in defence of India itself. Meanwhile, nationalist dissent was bubbling away inside the subcontinent. Gandhi himself said there was little to choose between British and German rule; as Nehru put it, inside their empire, the British behaved like fascists. It was easy, after the war, to write off the treachery of Subhas Chandra Bose, Gandhi's former deputy, who sought help from Hitler and the Japanese. But whom had he betrayed? His main fault was to think that either the Germans or the Japanese would seriously want to help him. But that the war should bring British colonial rule to an end was a view he shared with all his former Congress comrades.

Thus, viewed from outside Europe, the British war against nazism looks less like a moral crusade and more like defence of the global status quo. A war for liberty and self-determination? Not in the colonies, if Churchill had any say in the matter. Nor even in the Middle East where Churchill did make a critical and often overlooked strategic contribution. Had the Germans got sympathetic regimes to stay in place there to secure their oil supply, the war might have gone differently. British intervention in Syria, Egypt and Iraq prevented that and did much more - it laid the foundations for a new, short-lived empire of client states stretching from Libya to Iran. After the war, once India and Pakistan became independent, and the Australians and New Zealanders looked increasingly to Washington for protection from Asia, it was the Middle East where the British made their last imperial stand.

The global perspective is not one we should ignore. Viewed from India or Japan, the war was a matter of rival imperialisms, the culmination of more than a century of Europeans fighting over how to carve up the world. The irony is both Britain and Germany were too weak to defeat the other unaided. If Britain had stronger allies than Germany, this was as much the fault of the Nazis - stabbing Stalin in the back, contemptuous of the Spanish and French, the Hungarians and Italians - as it was a reflection of London's superior charms. The Germans lost their empire in Europe, the British lost theirs outside it.

The real lessons for both - but learned more readily since 1945 by the Germans - emerge starkly. Europe's internal rivalries cost it the global domination that it had won over the previous century and a half, and its war produced a new world, one in which Europe is still struggling to find a place. The courage of those who played their part in nazism's defeat should not be forgotten. But harping on about Britain's superior statecraft, or German perfidy, does nothing to acknowledge these changed realities. Is it too much to hope that a new perspective, simultaneously more sober and less parochial, may emerge from this latest round of commemorations?—Dawn/The Guardian News Service

Mark Mazower teaches history at Columbia University. His new book, No Enchanted Palace the end of empire and the ideological origins of the UN, is published by Princeton University Press