1945: End of World War Two
The collapse of British imperial power - all but complete by the mid-1960s - can be traced directly to the impact of World War Two.
The catastrophic British defeats in Europe and Asia between 1940 and 1942 destroyed its financial and economic independence, the real foundation of the imperial system.
Britain had survived the war, but its wealth, prestige and authority had been severely reduced.
It also erased the old balance of power on which British security - at home and abroad - had largely depended.
Although Britain was one of the victorious allies, the defeat of Germany had been mainly the work of Soviet and American power, while that of Japan had been an almost entirely American triumph.
Britain had survived and recovered the territory lost during the war. But its prestige and authority, not to mention its wealth, had been severely reduced.
The British found themselves locked into an imperial endgame from which every exit was blocked except the trapdoor to oblivion.