The Lucitania sunk, with several of your passengers on board. Not only that, apparently Germany was trying to drag Mexico into all of this with the promise of helping them "regain" states that originally belonged to them, like Texas.
Archduke Franz Ferdinand of Austria-Hungary was assassinated while attending a parade. His death, caused by a Serbian nationalist, caused an uproar. Austria-Hungary declared war on Serbia, and due to alliances, soon the entirety of Europe was at war.
The Technology and the Warfare
On 5/7/1915, a German u-boat sank a British passenger liner- the Lusitania. 1,200 people died, 128 of them American. On 2/24, Pres. Wilson saw a telegram intercepted by the British. It was a message from Germany to Mexico, seeking an alliance in exchange for assistance regaining US states which previously belonged to Mexico. These events pushed the US into WW1.
In the alliance system, all of the countries within an alliance agree to cause each other no harm until a certain goal is reached. The Central Powers consisted of Germany, Austria-Hungary, the Ottoman Empire and Bulgaria. The Allied Powers consisted of France, Russia, Britain, and the US.
The War Has Ended
Wilson's 14 Points
The war brought tons of new technology. Airplanes, armored tanks, and rapid fire machine guns and artillery are some examples. The most deadly invention brought by the war was poisonous gas- it caused choking, blindness, and severe skin blisters. Trench warfare was a new style of fighting where soldiers fire at one another from opposing trenches dug into the earth.
On 10/6, the head of the German government sent Pres. Wilson a note seeking an armistice based on the 14 points, but Wilson was unhelpful. The terms of the armistice were dictated by France and Britain. First, Germany was to pull back their troops on the Western front. Next, they were to cancel the Treaty of Brest-Litovsk. Lastly, they had to turn over their fleets of u-boats.
The Treaty made Germany take blame for the war and pay the Allies for war damages. Limits were placed on the size and nature of Germany's army. The Treaty called for an international organization called the League of Nations, which would give countries a place to meet, settle disputes civilly, and to punish anyone who broke the peace. Germany signed the treaty on 6/28/1919.