The First World War shaped the twentieth century. It sparked the Russian Revolution, and it launched America as a world power. The fault-line from its failed peace settlement led to a second terrible world war barely twenty years later.

The first months of the war on the Western Front were mobile, fast and dangerous; casualty rates were higher than with later trench warfare. The Germans were halted by the Allies at the Battle of the Mame, fell back to high ground and dug in. The Allies followed suit.