The First World War began on 28 July 1914 when Austria-Hungary declared war on Serbia, and it ended on 11 November 1918 when the Western Front armistice took effect. That four-year span destroyed four major empires—the Austro-Hungarian, German, Ottoman, and Russian—and cost roughly 20 million lives. The competitor overview covers the broad strokes, but it leaves out the specific diplomatic missteps of the July Crisis, the precise naval maneuvers that starved Central Power populations, and the structural causes that made the armistice inevitable long before November 1918.
This guide breaks down the exact timeline, the strategic turning points, and the often-overlooked events that shaped the conflict from its first shots to its final ceasefires.
The July Crisis and the Spark of 1914
The war didn't start because of a single bullet in Sarajevo; it started because European capitals had spent decades building a hair-trigger alliance system. When Archduke Franz Ferdinand was assassinated on 28 June 1914, leaders in Vienna, Berlin, St. Petersburg, and Paris miscalculated how quickly diplomatic posturing would spiral into total mobilization.
- 28 June 1914: Gavrilo Princip shoots Archduke Franz Ferdinand and his wife Sophie during an official visit to Sarajevo. Princip belongs to Young Bosnia, a revolutionary group aiming to free Slavic territories from Austro-Hungarian control.
- 5–6 July 1914: Kaiser Wilhelm II issues the infamous "blank check" to Austria-Hungary, pledging unconditional German support for punitive action against Serbia.
- 23 July 1914: Vienna delivers an intentionally unacceptable ultimatum to Belgrade, demanding full participation by Austro-Hungarian officials in the Serbian murder investigation within 48 hours.
- 28 July 1914: Serbia accepts most terms but rejects provisions violating its sovereignty. Austria-Hungary declares war and begins shelling Belgrade the next day.
Russia ordered partial mobilization on 30 July to protect Serbia, prompting Germany to declare war on Russia on 1 August and on France on 3 August. When German armies invaded neutral Belgium on 4 August to execute the Schlieffen Plan, Great Britain entered the fray, turning a regional Balkan conflict into a global war. You can read primary diplomatic records from this period through the Library of Congress.
Stalemate and Attrition: 1915 to 1916
By the end of 1914, the mobile warfare envisioned by generals had bogged down into defensive trench networks stretching 400 miles from the Swiss border to the North Sea. Both sides spent the next two years trying to break the deadlock through industrial-scale slaughter.
The Gallipoli Campaign of 1915 saw Allied forces attempt to knock the Ottoman Empire out of the war and open a sea lane to Russia. It failed disastrously, costing over 140,000 Allied casualties. Meanwhile, the naval blockade imposed by the British Royal Navy starved German industrial and agricultural supply chains, leading to widespread civilian malnutrition known as the "Turnip Winter" of 1916–1917.
The grinding nature of this era became clear at the Battle of Verdun, which lasted from February to December 1916. German Chief of Staff Erich von Falkenhayn aimed to "bleed France white" by attacking a symbol of national pride. The French held the line, but combined casualties approached 700,000. To relieve Verdun, British and French forces launched the Battle of the Somme in July 1916. On the first day alone, the British Army suffered 57,000 casualties, marking the bloodiest single day in British military history.
The Breaking Point: 1917
The year 1917 rewrote the military balance. Exhausted by mounting casualties, domestic starvation, and economic collapse, the Russian population revolted in March 1917, forcing Tsar Nicholas II to abdicate. The provisional government stayed in the war, but the Bolshevik seizure of power in November 1917 led to the immediate cessation of Russian hostilities and the formal signing of the Treaty of Brest-Litovsk in March 1918.
Germany's high command thought this Russian collapse gave them a final window of victory. They could now transfer nearly fifty divisions to the Western Front. However, Germany's decision to resume unrestricted submarine warfare in early 1917—sinking American merchant ships crossing the Atlantic—pushed the United States past its isolationist stance.
- 6 April 1917: The United States formally declares war on Germany, injecting billions of dollars in loans and millions of fresh troops into the Allied camp.
- June 1917: The first units of the American Expeditionary Forces land in France under the command of General John J. Pershing.
- November 1917: The Battle of Cambrai demonstrates the first massed use of tanks in warfare, signaling the eventual end of traditional infantry-and-cavalry dominance.
The Final Hundred Days: 1918
Realizing that American reinforcements would soon make a German victory impossible, General Erich Ludendorff launched the Spring Offensive in March 1918. German stormtroopers made rapid territorial gains, pushing deep into Allied lines. Yet these elite units outran their supply lines, and German reserves ran dry.
The Allies struck back in August 1918 with the Hundred Days Offensive. Coordinated attacks by British, French, Australian, Canadian, and American armies shattered German defensive lines at the Battle of Amiens. Concurrently, Allied forces in the Middle East and the Balkans dismantled the Ottoman and Bulgarian military structures.
By October 1918, Germany's allies had surrendered, its army was in retreat, and revolution loomed at home as sailors mutinied in Kiel. Kaiser Wilhelm II abdicated on 9 November, fleeing to the Netherlands.
The Armistice and Aftermath
The fighting officially stopped at 11:00 a.m. on 11 November 1918. Negotiated in a railway carriage in the Compiègne Forest, the armistice required Germany to evacuate all occupied territory, surrender vast quantities of military equipment, and hand over its submarine fleet.
The human toll was staggering. Approximately 10 million military personnel and 7 million civilians died, with another 21 million wounded. The economic and social devastation laid the groundwork for the Imperial War Museums archives, which preserve the ongoing historical record of how these four years reshaped the modern world.
Frequently Asked Questions
Why did the war last four years if everyone expected it to be short?
Military planners in 1914 expected a war of rapid movement powered by railways and artillery. Instead, the invention of the machine gun, rapid-firing field artillery, and barbed wire gave the defense an overwhelming advantage over the offense. Neither side could outflank the other, forcing troops to dig in and wait for industrial production to catch up with tactical innovation.
What role did the Ottoman Empire play in WWI?
The Ottoman Empire entered the war on the side of the Central Powers in late 1914, opening major new fronts in the Middle East, the Caucasus, and the Gallipoli Peninsula. Its collapse in late 1918 led to the partitioning of the Middle East by Britain and France through the League of Nations mandate system, drawing borders that persist today.
Was the armistice a peace treaty?
No. The armistice was merely a suspension of hostilities. The formal state of war officially ended months later with the signing of the Treaty of Versailles on 28 June 1919, which imposed severe territorial and financial penalties on Germany.
