In 1914, the First World War broke out in Europe. The United States repeatedly declared neutrality and continued trading with both sides. The war involved the use of poison gas, and casualties on both sides were enormous. Germany carried out unrestricted submarine warfare, attacking all merchant ships; several American merchant vessels were sunk, provoking anger among the American public. In March 1917, the United States obtained a copy of a telegram sent by Germany to its ambassador in Mexico, urging Mexico to join the war against the United States, with Germany promising to help Mexico recover three southern U.S. states. The United States was enraged. In April 1917, the U.S. Congress declared war on Germany, and President Wilson sent large numbers of troops to Europe to fight against Germany.

The bloodshed of the First World War exceeded that of all previous wars. 1918 was the final year of the war, and it did not end easily, as German forces continued their last desperate resistance.

The Battle of the Argonne Forest was extremely fierce, with thousands of soldiers killed. The Allied forces advanced step by step, while German troops retreated repeatedly. German commanders lost hope. In September 1918, when Kaiser Wilhelm II summoned them, the army commander-in-chief reported that Germany would lose the war. Germany had no choice but to return occupied territories and seek a negotiated peace. Conditions within Germany were also dire: people were starving, and revolutionary groups were plotting to overthrow the government. The Kaiser agreed that seeking peace before Germany was completely destroyed was the best option.

Kaiser Wilhelm II sent a secret letter to U.S. President Wilson, proposing immediate peace negotiations to end the war. Wilson received the letter and replied directly, asking whether Germany could accept the peace proposal he had put forward several months earlier. At this time, German submarines intensified their attacks on Allied shipping; two passenger ships were sunk, killing 820 passengers, many of them women and children.

President Wilson was shocked. He told the Germans that he would not negotiate peace with such an inhumane enemy. In late October 1918, Wilson sent Germany a final letter proposing a solution that would strip Germany of its ability to wage war. He stated that Germany must commit to withdrawing its troops from all Allied territories and must shut down its arms factories. Wilson also said that the Allies would negotiate only with a government that truly represented the German people, not with the military authorities.

The newly appointed German chancellor, Prince Maximilian of Baden, received Wilson’s letter and successfully persuaded Kaiser Wilhelm II to dismiss those responsible for Germany’s military policy.

Britain opposed freedom of navigation at sea, believing it would make the naval blockade against Germany impossible. France and Italy opposed the creation of a new international organization. Wilson called this organization the League of Nations.

In 1918, under Wilson’s mediation, the Allies entered into peace negotiations with Germany. To resolve disagreements among the Allied powers, Wilson sent advisers to Europe to meet with the leaders of the Allied countries.

Many Allied leaders believed that Wilson was too lenient toward the defeated nation. However, they ultimately agreed to use Wilson’s plan as the starting point for peace negotiations. In early November 1918, the situation in Germany continued to deteriorate. The German military had no choice but to negotiate with the Allies.

The peace terms shocked the German delegation. The Allied conditions were extremely harsh: Germany had to withdraw from all occupied territories; it had to relinquish Alsace-Lorraine, a region taken from France and controlled by Germany for fifty years; it had to give up most of its weapons, including aircraft, submarines, and warships; and it had to hand over large numbers of trucks, locomotives, and other equipment.

The German delegation stated that they would not sign such a treaty, arguing that Germany was not surrendering but merely requesting an armistice. However, the German government was collapsing. Kaiser Wilhelm II ultimately abdicated and left Germany. A new cabinet was formed, and the new prime minister declared Germany a republic.

After lengthy negotiations, Germany finally accepted the Allied terms. A few hours later, the armistice took effect. This bloody war finally came to an end.

The Paris Peace Conference and Europe’s Decline

After the armistice, the nations convened at the Palace of Versailles in Paris for a conference known as the Paris Peace Conference. The conference formally brought World War I to an end. After the war, Britain, which had previously been the world’s financial center and dominant global power, ceded its position to the United States. The war also weakened France, Italy, and Germany. The United States emerged as the world’s leading power, while Japan transformed from a debtor nation into a creditor nation and occupied Qingdao Bay and the Shandong Peninsula in China, areas that had previously been within Germany’s sphere of influence.

World War I completely ended America’s “isolationism,” making it the leading power actively involved in international affairs. Wilson sought to build a world in which people abandoned hatred, worked together, and avoided war. He proposed the establishment of the League of Nations, which would provide fair arbitration in disputes, prevent future wars, and ensure lasting peace.