The Great War from Sarajevo to Versailles: the July Crisis, the trenches of the Marne, Verdun and the Somme, America's entry, Russia's revolution, and the Hundred Days that ended it. Red marks battles and tragedies, green marks Allied milestones and the peace.
Gavrilo Princip shoots Archduke Franz Ferdinand of Austria-Hungary and his wife Sophie in Sarajevo. The assassination triggers the July Crisis that drags Europe's alliance system into war.
One month after the assassination, Austria-Hungary declares war on Serbia. Within a week Russia, Germany, France and Britain are all at war.
Germany invades neutral Belgium under the Schlieffen Plan, bringing Britain into the war the same day. The western front of the Great War opens.
French and British forces halt the German advance just short of Paris. The German retreat to the Aisne begins four years of trench warfare on the Western Front.
Along stretches of the Western Front, German and British soldiers spontaneously stop fighting to sing carols, exchange gifts and play football in no man's land.
Germany releases chlorine gas against Allied lines at Ypres, the first large-scale use of poison gas on the Western Front, opening a terrifying new chapter in warfare.
Allied forces including the ANZACs land on the Gallipoli peninsula to knock the Ottoman Empire out of the war. The campaign becomes a costly eight-month stalemate before evacuation.
A German U-boat sinks the British liner RMS Lusitania off Ireland, killing 1,198 people including 128 Americans, hardening US opinion against Germany.
Germany attacks the French fortress city of Verdun, aiming to bleed France white. The ten-month battle costs over 700,000 casualties and becomes a symbol of French endurance.
The British Grand Fleet and German High Seas Fleet clash off Denmark in the war's only full-scale battleship engagement. Both sides claim victory; Britain keeps control of the North Sea.
The Anglo-French offensive on the Somme opens with nearly 60,000 British casualties on the first day, the bloodiest in British military history. Tanks debut in September; the battle claims over a million casualties.
Britain reveals an intercepted German telegram offering Mexico an alliance against the United States. Published in American newspapers, it pushes the US toward war.
Following unrestricted submarine warfare and the Zimmermann Telegram, the United States declares war on Germany, bringing fresh manpower and industry to the Allies.
The Third Battle of Ypres bogs down in rain and deep mud. The Allies take the village of Passchendaele in November at a cost of hundreds of thousands of casualties on each side.
Lenin's Bolsheviks seize power in Petrograd. Russia begins its exit from the war, freeing German divisions for the Western Front.
Soviet Russia signs a punishing separate peace with the Central Powers, surrendering vast territory and formally ending the war on the Eastern Front.
Germany launches Operation Michael, a massive last-gamble offensive that drives the Allies back forty miles before exhausting itself short of victory.
Allied forces strike at Amiens with tanks, aircraft and surprise, advancing eight miles in a day. Ludendorff calls it the black day of the German Army; the war's final Allied offensive has begun.
Over a million American soldiers join the largest offensive in US military history, grinding through the Argonne Forest toward the German rail hub at Sedan until the Armistice.
With Germany in revolution and the army collapsing, Kaiser Wilhelm II abdicates and flees to the Netherlands. A German republic is proclaimed in Berlin.
At 11 a.m. on the eleventh day of the eleventh month, the Armistice signed in a railway carriage at Compiègne ends the fighting. Some nine million soldiers have died.
Five years to the day after Sarajevo, the Allies and Germany sign the Treaty of Versailles, redrawing the map of Europe and imposing reparations that will haunt the peace.