How the First World War was finally won

One of the decisive factors that helped end the war in 1918 was that America had joined the conflict on the side of the Allies.

The United States had formally declared war on Germany in April 1917, but it took time for the country to mobilise its forces and sail them to Europe to participate.

However, prior to the official declaration of war, America had still been involved in the war by supplying weapons and resources to the Allies.

So, what changed America's mind from being a supporter to being a participant?

Firstly, on the 7th of May 1915, a British passenger ship called the Lusitania was sunk by a German U-boat.

Of the 1198 passengers that died, 128 were Americans, and the American public was angered by this.

When, in February 1917, the Germans announced a restarting of their unrestricted submarine warfare, Americans feared that more civilians would lose their lives.

On April 2, 1917, President Woodrow Wilson delivered a speech to Congress asking for a declaration of war, which was granted on April 6, 1917. 

By the summer of 1918, over one million American troops, known as the American Expeditionary Forces (AEF) under General John J. Pershing, had arrived in Europe.

Another factor that aided the Allies in their eventual victory was the adoption of a new kind of warfare.

For the last few years of the war, the different elements of the armed forces (army, navy, artillery, and air force) had operated separately, under different commanders and rules.

By 1918, a new idea had developed: each of these forces could work as a single unit, following a unified battle plan. This was called 'combined arms warfare'.

Under this approach, new tanks would be used as a moving shield for infantry units, who would shelter behind the machines as they slowly crept forwards.

This would protect the soldiers until they reached the trenches. Artillery would provide a screen of explosive shells that crept forward at the same speed as the tanks, which would destroy any enemy troops before the tanks and soldiers reached them.

Aircraft would act as scouts, relaying information back to the artillery about their speed and potential targets. 

The unified approach under the combined arms warfare model proved to be very effective, especially with the influx of new men and materials from America. 

Following Russia's departure from the war by the end of 1917, Germany was able to relocate a significant number of soldiers and resources from the Russian front to the Western front.

The German commander, Erich Ludendorff, knew that he had to try and win the war with the increased troop numbers before the Americans were ready.

From March to July 1918, he launched the 'Ludendorff Offensive' (also known as Kaiserschlacht , or 'Kaiser's Battle'), which was a massive attack all along the Western front in France, with the aim of reaching Paris and forcing the Allies to surrender.

The first few weeks of the German attack were very effective, as the Germans gained more ground than they had since 1914.

They even about 56 miles (90 kilometers) from Paris during the Second Battle of the Marne in July 1918.

However, by July 1918, the Germans were running out of men and resources, and the advance slowed to a halt.

The constant blockades of German port cities by the British navy had resulted in food shortages back home and the German people were growing angry with the failure to win the war.

By this stage, the Americans were ready to join the Allied attack and push the Germans back.

In August 1918, the Allies began their counterattack, called the 'Hundred Days Offensive'.

Across a broad length of the Western front in France, Allied armies, using combined arms warfare, launched a massive assault against German lines.

The large number of American troops, the use of combined arms warfare, and the depleted German resources meant that the German army began retreating and giving up more land than they had gained.

The Meuse-Argonne Offensive, which lasted from September 26 to November 11, 1918, was the largest operation of the American Expeditionary Forces and a crucial part of the final Allied push.

By October 1918, it was clear that Germany was going to lose World War One.

Thanks to the British naval blockade, which had been in place since the early days of the war, the German economy was in ruins, with severe food shortages, strikes, and widespread public unrest.

General Ludendorff resigned from his military role, the German navy stopped following orders, and even the German Kaiser, Wilhelm II, abdicated on the 9th of November 1918.

On 11th November 1918, the leaders of both sides of the conflict met in a railway carriage and signed an agreement to cease hostilities, known as the 'Armistice'.

World War One was finally over.

Even though the war ended in November 1918, Europe still had to work out how to fix all of the damage that had been caused over the last four years of war.

Sorting out the consequences of the most brutal war in human history required a lot of countries to hold a lot of meetings to arrange a fair deal for everyone.

These meetings were arranged to happen just outside of Paris, in the palace of Versailles, during 1919. 

Lloyd George of Great Britain, Orlando of Italy, Clemenceau of France and Woodrow Wilson from America were the most important leaders who facilitated the discussions in order to draw up a treaty to assign blame and who would pay the costs from the war.

Woodrow Wilson arrived at the meetings with a 14-point plan for how to avoid any more world wars.

These points called for more openness between countries and that an international organisation should be created that could act as a 'referee' between arguing nations to avoid the need for war.

Wilson hoped that the negotiations between the different countries would be mutually agreeable, based upon his recommendations. 

However, there were deep resentments that meant that the Versailles conference did not go as smoothly as Wilson had hoped.

The French wanted Germany to suffer a severe punishment for their role in starting the war.

Lloyd George also wanted Germany to be heavily penalised, but worried that being too harsh would encourage communism to spread from Russia into Germany, which would be a new threat to future peace and security in Europe. 

Eventually, the final version of the Treaty of Versailles was signed on the 28th of June 1919. There was a total of 440 statements, known as clauses, in the treaty. 

It agreed to create an international organisation called the League of Nations, to police world peace.

It also stated that Germany was to accept full blame for starting World War One, which is known as the 'War Guilt Clause' (Article 231).

It forced Germany to pay a fine of 132 billion gold marks (roughly equivalent to £6.6 billion), called 'reparations'.

To prevent Germany from starting another war, the treaty also limited the German army to 100,000 soldiers, and they were not allowed to have any tanks or an air force.

The German navy were only allowed six battleships and no submarines.

The terms that Germany was forced to accept from the Treaty of Versailles were considered to be too harsh by many people.

In fact, the anger at how harsh they were amongst Germans would be used by political groups to begin the journey towards World War Two.