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.
The Schlieffen plan was a plan made by Germany to fight France and Russia. The battle of Marne led to a stalemate which prevented the Germans from enacting the plan and prevented their attempts to siege Paris and taking it completely. Not only did they stop the assault, but the Germans actually feared that there was a possibility of actually suffering defeat by the French Army.
In part, Europeans began sea exploration in the hopes of expanding their empires and colonising new countries. They also began sea exploration to find new trading partners, new goods and even new trade routes. Some set out also to discover new areas of the world, especially as when sea exploration first began there were still sections of the world that still remained unknown in Europe - e.g. on maps in the 16th century many of the continents in the Southern Hemisphere were marked wrongly or did not exist