World War I: The 26-day Battle of Belleau Wood near the Marne River in France ended with American forces finally clearing that forest of German troops.

World War I or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. Main areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. There were important developments in weaponry including tanks, aircraft, artillery, machine guns, and chemical weapons. One of the deadliest conflicts in history, it resulted in an estimated 30 million military casualties, plus another 8 million civilian deaths from war-related causes and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.

The Battle of Belleau Wood was a major battle that occurred during the German spring offensive in World War I, near the Marne River in France. The battle was fought by the U.S. 2nd and 3rd Divisions along with French and British forces against an assortment of German units including elements from the 237th, 10th, 197th, 87th, and 28th Divisions. The battle has become a key component of United States Marine Corps history.

The Marne is a river in France, an eastern tributary of the Seine in the area east and southeast of Paris. It is 514 kilometres (319 mi) long. The river gave its name to the departments of Haute-Marne, Marne, Seine-et-Marne, and Val-de-Marne.