Memorial Day: America’s 7 costliest wars

3. World War I

Often called “the war to end all wars,” World War I began in 1914 after a Serbian nationalist assassinated Archduke Franz Ferdinand, heir to the Austro-Hungarian Empire.

The conflict eventually involved alliances of nations fighting across Europe, Africa and Asia, and contributed to the rise of Nazi Germany and the Soviet Union.

Although the United States did not officially join the Allies until 1917, more than 116,000 Americans died in the war. About 53,000 died in combat, while more than 63,000 died from disease and other causes.

“By September 1918, the [American Expeditionary Forces] began independent operations and played a key role in the ‘Hundred Days Offensive,’ which ended the war,” explained the National Park Service.

“The Americans helped break the fortified Hindenburg Line at St. Quentin, and at St. Mihiel, half a million American and 100,000 French troops, supported by 1,500 Army Air Service aircraft, took back in four days territory the Germans had held for almost four years.”