On June 28 1914, the assassination of Archduke Francis Ferdinand triggered the war. However, this event did not cause the United States to join the war. After the assassination, Austria Hungary declared war on Serbia. As the war progressed, Russia, France, and Britain joined on the side of the Allies because of alliances to each other. Germany and the Ottoman Empire later joined, because of their own secret alliances to each other. Germany, Bulgaria, the Ottoman Empire, and Austria-Hungary formed the Central Powers.
The United States later joined on the side of the Allies for various reasons. On May 7, 1915, the British Lusitanian was sunk, and 128 Americans lost their lives. Although the ship was carrying weapons, the Germans did not warn the ship before sinking it. This was a violation of international law. After two more similar events, the Germans made the Sussex Pledge, pledging not to sink any more ships.
However, the US had to convince Britain to end its blockade.
After threatening our neutrality, another incident occurred concerning Germany. The Zimmermann note was sent to Mexico, but intercepted by the British. This note stated that Germany would support Mexico if war were to break out in the United States. On April 6, 1917, the United States declared war. World War 1 brought about the innovation of war tactics and equipment used during the war. Such examples are trench warfare, U-boats (submarines), cannons, poison gas, tanks, and flamethrowers.
On November 11, 1918, the war was finally at an end. The Allies had defeated the Central Powers. The war resulted in the Treaty of Versailles. The United States had a main goal of receiving a fair settlement from this treaty. The key points of the treaty were, Secret alliances abolished Free trade, Military Buildups prohibited Self-determination, and...