World War I was a global human conflict taking place from July 28, 1914, to November 11, 1918. It was fought between the Central Powers, consisting of Germany, Austria-Hungary, and the Ottoman Empire, and the Allied Powers, consisting of France, the United Kingdom, Russia until 1917, and the United States after 1917.
On June 28, 1914, Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, was assassinated in Sarajevo by Gavrilo Princip, a Serbian nationalist and member of the Black Hand terrorist organization. Austria-Hungary immediately demanded heavy concessions from Serbia, and upon their refusal, declared war on July 28. Germany, under Kaiser Wilhelm II, and the Ottoman Empire entered the war on Austria-Hungary's side. Russia, under Tsar Nicholas II, took up Serbia's cause. France and the United Kingdom joined the war on Russia's side.
Following the Schlieffen Plan, Germany launched a quick offensive through neutral Belgium and into northern France, hoping to knock them out quickly so they could direct their full attention to Russia. Before the Germans could reach Paris, the British Expeditionary Force, 75,000 men strong, met them in combat in the First Battle of the Marne. The German attack was blunted, and the Western front settled into a bloody stalemate.
In the fall of 1914, each side dug extensive trench systems to protect against artillery bombardment. On Christmas Eve, an informal truce was agreed upon by the soldiers, and Christmas Day was spent trading cigars, caroling, and in one case playing a match of association football.
In 1916, the Battle of Verdun and the Battle of the Somme occurred nearly simultaneously. Both battles cost nearly half a million lives, and accomplished very little. The Western front sank into the same routine of endless artillery barrages, futile charges into no-man's land, and relentless machine gun.
In 1917, the United States entered the war, and began pouring troops into northern France. They helped defeat the German spring offensive, and began pushing back the Germans into their own territory.
By 1918, the Allies had reached the Hindenburg Line, Germany's primary line of defense. Although this held them back for a while, it was soon breached, and under the combined pressure of an Allied onslaught, a naval mutiny, and widespread insurrections, Germany surrendered on November 11, 1918.
At the beginning of the war in 1914, Russia launched an offensive in two directions: one against Austria-Hungary in Galicia, the other against Germany towards Krakow. The Galician offensive was a resounding success and the Russians had occupied it within months.
The offensive towards Krakow resulted in the Battle of Tannenberg, which was a blow to the Russian momentum, but ultimately fairly unimportant. Germany felt extremely threatened and transferred the bulk of its forces from the Western Front to the east. The German Army managed to make only small gains, but the ultimate goal of halting the Russian advance was achieved. 1915 saw the Germans push fighting away from Germany and closer to the Vistula River in Lithuania, although Austria-Hungary had begun to collapse and failed to contribute much to the war effort.
In July 1916 the Brusilov Offensive, led by Alexei Brusilov, managed to make a significant dent in German lines, but this momentum couldn't be sustained because of ammunition and supplies shortages. These shortages meant that the Russians had to begin a systematic retreat. Once the Russian economy had transitioned to wartime production, which was around late 1916, the situation began to improve and the retreat was halted on a Riga-Pinsk-Ternopol line.
The situation was beginning to shift in Russia's favor, except the February Revolution forced Tsar Nicholas II to abdicate, and the system of command was upset. The provisional government's weak leadership and restrictions on officers' authority led to decreased morale, and by mid 1917 the Russian economy was nearing collapse. General food shortages and rioting in cities eventually reached the military, which had been keeping the Germans stationary since late 1916. Bolshevik agitators and other factors caused mutinies and the Russian front fell apart.
By 1918, when the Bolsheviks had taken over, the situation was absolute chaos and the Treaty of Brest-Litovsk was signed on March 3, which halted the war. In the treaty, the Bolsheviks promised to honor the independence of Finland, the Baltic states, and Ukraine.
The Ottoman Empire and Russia, traditionally enemies, fought over the Caucasus. The Russians were able to push back the Ottomans, but in 1917 Russia collapsed and the Ottomans retook most of their lost territory. It was also during this time that the Armenian Genocide took place.
Winston Churchill, the First Lord of the Admiralty, proposed a daring plan to capture the town of Gallipoli, near Istanbul in the Ottoman Empire. Thousands of troops, including large numbers of Australians and New Zealanders, landed on the bay. However, the Ottoman military had been substantially modernized by the Germans, and they were mowed down by machine gun fire.
In 1917, T.E. Lawrence, better known as Lawrence of Arabia, was dispatched by the British to Ottoman-controlled Arabia to begin an insurgency against the Ottomans. The Arabs, who disliked Turkish rule, were quick to follow him, and the Ottomans effectively lost control of the Arabian Peninsula.
The Japanese fought on the Allied side. They captured German territories in the Pacific and in China. However, they were poorly rewarded at the Treaty of Versailles, and this brewed resentment that led up to World War II.
The war left much of Europe in ruins. Nearly 16 million people were dead, many of them civilians. The Russian Empire collapsed, and the Soviet Union was formed after the bloody Russian Civil War. The German Empire was also overthrown, and the Weimar Republic was established. Austria-Hungary splintered into Austria, Hungary, Czechoslovakia and the Kingdom of Yugoslavia. The Ottoman Empire became the nation of Turkey, and its former Arab territories became colonies of France and the United Kingdom.
The Treaty of Versailles imposed the Allied victory terms on the Central Powers, primarily Germany. Massive war reparations were required, and Germany was effectively disarmed. Their army was limited to a paltry 100,000 men, and their navy was scrapped at Scapa Flow. Additionally, the territory of Alsace-Lorraine was returned to France, and the United Kingdom received many of Germany's former colonies. These war terms were despised by Germans and their resentment was an indirect cause of World War II.