January 1917. The Zimmermann Telegram is released in the United States. This helps makes Americans angry at Germany. That helped the Allies because it helped cause the US to enter the war.February 1917. Germany resumes unrestricted submarine warfare. Germany had stopped sinking ships without warning because it did not want to antagonize the US. However, it now decided that it had to resume unrestricted use of its submarines so it could try to end the war quickly. This helped the Allies because it helped bring the United States into the war.April 1917. The United States enters WWI. This did not have an immediate effect, but it would be a major factor because it eventually gave the Allies more soldiers and supplies to use in the war.April 1918. The Allies stop a German offensive on the Western front. The Germans launched the offensive to try to end the war before the American soldiers really joined the fighting. Battles include the Battle of Cantigny.
