Watch World War 1 in Color online: Episode 6 Victory and Despair

1918 was the ultimate 'Game of Two Halves'. As it opened, Russia's collapse meant that Germany had a brief window of opportunity to win the war in the West before the strength of the new American armies made the Allies unbeatable. In March 1918, Ludendorff launched the first of a series of offensives - using new and daring Stormtroop tactics - to break the stalemate and knock the Allies out. But they hung on grimly until the storm abated. Then in July the Allies began a series of rolling offensives, led largely by the British and American armies. Using a combination of artillery, armour, air power, and mobile infantry which had been perfected in more than three bitter years of trial and error, they started to push the exhausted Germans back all along the front, until defeat was inevitable.

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