Summary
Highlights
Australia took German New Guinea, and the Allies attacked German colonies in Africa, enlisting locals as soldiers. Japan and Italy joined the Allies, with Japan expanding its empire and Italy switching sides after promises of territory from Austria-Hungary. The Ottoman Empire joined the Central Powers after some politicians unilaterally attacked Russia. The Ottomans' entry was a concern for Britain due to their oil interests in the Middle East. The Ottomans failed in attacks against Russia and the Suez Canal, and an Allied attempt to take the Dardanelles also failed. The Ottomans blamed Armenians for their losses, leading to the Armenian Genocide. German attempts to incite jihad in Afghanistan against the British also failed.
To break the stalemate, Germany abandoned the rules of modern warfare, using Zeppelin raids, chlorine gas attacks on trenches, and sinking civilian ships with U-boats, including the Lusitania, which swayed US opinion against them. The Allies also later used chemical warfare and hid anti-submarine weapons on civilian ships.
Bulgaria joined the Central Powers, helping them defeat Serbia. Austrian-Hungary then entered neutral Albania in a 'friendly invasion' to chase down Serbians. Portugal also became an enemy of Germany due to its ties with the Allies. The only major sea battle, the Battle of Jutland, occurred between expensive new battleships, resulting in damage to both sides, after which they avoided further direct naval confrontations. The UK began conscripting men for the army.
The Battle of Verdun, the longest and bloodiest battle, began with a German attack, followed by the British Battle of the Somme, which saw 60,000 British casualties on the first day and the first use of tanks. Russia launched a major offensive to aid the French but ran out of supplies. Romania joined the Allies but was quickly overwhelmed. Greece experienced a national schism over joining the war, eventually reuniting and joining the Allies. In the Middle East, Russia pushed into Ottoman territory, and the British made landings in Mesopotamia to protect oil fields, but an attempt to take Baghdad failed until a new offensive, aided by Lawrence of Arabia and Arab tribes, devastated Ottoman supply lines.
By 1917, all sides were exhausted, with mutinies, starvation, and depleted supplies. Russia, facing internal unrest and a 'crazy magic homeless guy' influencing decisions, experienced uprisings and revolutions, leading to the overthrow of the Tsar and then the new government by the Bolsheviks, who pulled Russia out of the war. This allowed Germany to focus solely on the Western Front.
The US, which had been enriching itself by selling supplies to the Allies, was increasingly likely to join the war. Germany's telegram to Mexico, proposing an attack on the US, was intercepted and became the final straw, leading to American troops being sent to Europe. Facing fresh American forces, Germany launched a desperate final offensive on the Western Front, hitting hard at the Somme and pushing the Allies back multiple times. However, the Allies, with increasing American support, held the line and launched a counter-attack.
The Central Powers began collapsing, with Bulgaria surrendering first, followed by the Ottoman Empire, Austria-Hungary, and finally Germany on November 11, 1918. In the peace treaty, Germany was forced to reduce its military, accept war guilt, and pay reparations. The devastating war, which resulted in millions of deaths, was followed by a brief period of peace for about 20 years.