The First World War; arguably the second-worst war in history (behind WWII), was a worldwide war, which lasted from 28th July 1914 to the 11th November 1918.

It all started when the Austro-Hungarian empire declared war on Serbia (after the Black Hand assassinated the heir, Archduke Franz Ferdinand). Russia, in the Triple Entente, helped Serbia, France helped Russia, and Britain initially stayed out of the war. Germany helped the Austro-Hungarian empire, and Italy stayed out of the war.

Germany's tactics were to quickly shred through France's defences and invade France, then swiftly return to the Eastern Front and defeat Russia. However, there was one flaw in this plan. The French had many forts along the border, which made invading quite difficult, so Germany invaded Belgium. The British defended the Belgians and were now in the war. On the 12th August, Britain & France also declared war on the Austro-Hungarian Empire. On the 23rd August, Japan sided with the Entente, viewing it as a way to get Germany territories in and around the Pacific.

The Germans invasion of France was stopped at the Battle of the Marne, and by the end of 1914, trench warfare had begun, which lasted (largely) without any difference until 1917. The Germans put heaps of pressure on French forces when they attacked Verdun on the 21st February 1916, so much that the British had to start their own battle further north, at the Somme. The British lost 57,000 men on the first day, and by the end of the battle, they had lost 456,000 men, with France losing 200,000 and the Germans losing ~450,000.

On the Eastern Front, there were much larger territorial changes. Serbia had been invaded in 1915, and Romania joined in 1916, only to be invaded in 1917.

In November 1914, the Ottoman Empire joined the Triple Alliance (Central Powers) and opened up fronts in the Cacauses, Mesopotamia and the Sinai Peninsula. By the time 1915 had rolled around, Italy had left the Central Powers and sided with the Triple Entente, but, like the western front, they couldn't be invaded or invade Austro-Hungary. Around the same time, Bulgaria joined the Central Powers.

After the sinking of 7 US Merchant Navy ships by German Submarines, the sinking of the Lusitania in 1915 (which had 120 Americans on board) and the Zimmermann Telegram being intercepted by the British, which was a plan by the Germans to get Mexico to invade the US, which ultimately led the US to join the war in 1917.

Russia's Tsar kings were overthrown in the 1917 February Revolution, with the Provisional Government taking its place, only to be overthrown by the Soviet Socialist Republic in the October Revolution. The Soviets signed the Treaty of Brest-Litovsk, which ended Russia's part in the war. Russia's withdrawal from the war allowed the transfer of large amounts of German troops to the Western Front. This resulted in the German March 1918 Offensive, where they initially made lots of progress. However, this was not to be, as the Allies drove them back during the Hundred Days Offensive. On the 28th September, military leaders in Germany requested an armistice. On 4th November 1918, the Austro-Hungarian Empire agreed the Armistice of Villa Guisti. With the military giving up, and the German Revolutions of 1918-19, Kaiser Wilhelm II abdicated on 9th November 1918, with Germany signing an armistice on the 11th hour, of the 11th day, of the 11th month, 1918. The war was over.