Which U.S. conflict was known as "The Great War" before World War II?

"The Great War" refers specifically to World War I, which was fought from 1914 to 1918. When it occurred, it was the largest conflict in history at that time, involving many of the world’s great powers, and it was often labeled as such before the advent of World War II. The scale, destruction, and loss of life were unprecedented, leading to the belief that it would be "the war to end all wars."

The name "The Great War" was in use until the 1930s, when the outbreak of World War II necessitated a reevaluation of its title, resulting in the retroactive labeling of World War I as the first part of a series of global conflicts. This historical context underscores the significance of World War I in shaping modern warfare and international relations.

In contrast, the other conflicts mentioned—World War II, the Korean War, and the Vietnam War—do not carry the designation of "The Great War" and occurred later in the timeline of U.S. military history.