On 6 September 1914, 600 Paris taxis, we are told, saved France from calamity.

They transported 6,000 soldiers to reinforce a French and British attack on the five German armies blundering over the plains east of Paris (now the home of Disneyland Paris).

Their arrival tipped the balance in one of the most important battles in history. A lightning German advance through Belgium and northern France in the first weeks of the war was checked. The German commanders panicked and retreated behind trench lines from the North Sea to Switzerland.

The total taxi-meter bill to take the 7th Infantry Division to the Battle of the Marne, settled by the French war ministry, came to Fr70,102, or £3,500.

If you accept the legend of "the taxis of the Marne", there was another, bloodier bill. The Marne prevented an early German victory and prolonged the First World War through a further four years and two months of mass slaughter.

Shape Created with Sketch. In pictures: A history of the First World War in 100 moments Show all 149 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. In pictures: A history of the First World War in 100 moments 1/149 First World War Supporting troops of the 1st Australian Division walking on a duckboard track near Hooge, in the Ypres Sector Getty Images 2/149 First World War Final moments: The Archduke of Austria Franz Ferdinand with his wife Sophie in Sarajevo minutes before his shooting AP 3/149 First World War Arresting Princip's fellow conspirator Nedeljko Cabrinovic after a failed attempt to kill the Archduke on the same day Getty Images 4/149 First World War Crowds in central London cheer Britain's declaration of war on Germany Getty Images 5/149 First World War The innocents: New recruits, with bicycles, training with the British Army in 1914 Getty 6/149 First World War 1914: A lone soldier with a bicycle stands amid the remains of a German motor convoy which lines a country lane after an attack by French field guns in the battle of the Aisne in France Topical Press Agency/Getty Images 7/149 First World War Troubled waters: The Cambridge eight included John Andrew Ritson (fourth from cox) Museum of London, Christina Broom 8/149 First World War John Andrew Ritson (left) Museum of London, Christina Broom 9/149 First World War Dennis Ivor Day Musuem of London; Christina Broom 10/149 First World War German infantry advance through Belgium in August 1914 Getty Images 11/149 First World War Civilians near the Austrian lines in Serbia are strung up – probably as a reprisal for guerrilla resistance to the invaders Miroslav Honzík/Hana Honzíková 12/149 First World War Captured soldiers of the Russian 2nd Army after their defeat at the Battle of Tannenberg Getty Images 13/149 First World War Wounded and exhausted British and Belgian soldiers retreating after the Battle of Mons Getty Images 14/149 First World War Crowds gather outside a recruitment office Getty Images 15/149 First World War French General Joseph Joffre (second right), Commander- in-Chief of the French Armies, and General Michel Joseph Maunoury (right) on the front during the First Battle of the Marne. Six hundred scarlet taxis were requisitioned, at a cost of Fr70,102, to ferry reservist troops to the Battle of the Marne in 1914 Getty Images 16/149 First World War A French firing squad escorts a deserter to his execution in November 1914 Getty 17/149 First World War One of the trenches from which deserters tried to escape Getty 18/149 First World War German soldiers in Wirballen, a border town between the German Reich and Russia Mary Evans Picture Library 19/149 First World War Carl Hans Lody, who spied in Britain Popperfoto/Getty 20/149 First World War Up to 12 million letters a week were sent to the front line via the wooden sorting office hastily set up in Regent's Park in 1914 Royal Mail 21/149 First World War Survivors from SMS 'Gneisenau' in the sea off the Falkland Islands, with HMS 'Inflexible' in the background, 8 December 1914 Getty Images 22/149 First World War The ruins of the cloth hall and cathedral in Ypres during WWI Getty Images 23/149 First World War Margot Asquith, the Countess of Oxford and Asquith and the wife of Britain's wartime leader Getty Images 24/149 First World War A wounded American in a London hospital reads a magazine with a red cross nurse by his bedside. A. R. Coster/Topical Press Agency/Getty Images 25/149 First World War A mass execution by firing squad following the unsuccessful Singapore mutiny of 1915 rebelsindia.com 26/149 First World War Indian soldiers serving