On April 22, 1915, a wave of suffocating gas released from cylinders implanted in the ground by German specialist troops suffocated the Allied line on the northern end of the Ypres salient, causing panic and a struggle to survive a new form of weapon.

On May 7th, 1915, the German's submarine (U-boat) U-20 bashed and sank the Lusitania. About 1,959 men, women, and children on board, and 1,195 had died, including 123 Americans.

On April 2, 1917, the U.S. president, Wilson, decided to break off their diplomatic ties due to Germany's violation of its pledge to suspend unrestricted submarine warfare.

On July 28, 1914, Austria-Hungary declares war on Serbia after they rejected the terms in an ultimatum sent to them by Austria on July 23, after Archduke Franz Ferdinand, heir to the Austria-Hungary throne, had been assassinated by Serbian student, Gavrilo Princip, in Sarajevo.

On March 7, 1917,  Russians decided to start a revolution due to, Czar was ineffective leader, lots of poor hungry people because of food shortages, inequality in income, Russia was in deep debt, and no basic human rights.

On April 4, 1917, prior to the incident of Lusitania being sunk, losing many of America's citizens, Wilson approved a resolution declaring war with Germany. 

On March 3, 1918, Russia signed a treaty with the Central Powers, ending its participation in World War I. Lenin believed that Russia must end its participation in the war so that the nation could focus on creating a more communist state.

On November 11, 1918, after over four years of horrific fighting and the loss of millions of lives, the guns on the Western Front fell silent. The fighting in the war continued elsewhere, however, the armistice between Germany and the Allies was the first step to ending World War I.