World War I

The National Defense Act of 1916 was passed while the Mexican bandit and revolutionary Pancho Villa was raiding the border towns of the Southwest. The entire National Guard was called to active duty by President Woodrow Wilson, and within four months 158,000 Guardsmen were in place along the Mexican border.

Guardsmen stationed on the border in 1916 saw no action. But in the spring of 1917, the U.S. declared war on Germany and entered World War I, and the Guardsmen had a chance to put their training to good use.

The National Guard played a major role in World War I. Its units were organized into divisions by state, and those divisions made up 40% of the combat strength of the American Expeditionary Force. Three of the first five U.S. Army divisions to enter combat in World War I were from the National Guard. Further, the highest number of World War I Medal of Honor recipients were from the 30th Division, made up of National Guardsmen from the Carolinas and Tennessee. The years between World Wars I and II were quiet ones for the Army and for the National Guard. The most significant developments occurred in what would become known as the Air National Guard.

The National Guard had a few "aeroplanes" before World War I, but only two New York aviation units were formally organized. After the war, Army organization charts called for each division to have an observation squadron (the primary mission of aircraft in those days was reconnaissance), and the National Guard was eager to form their own squadrons. By 1930, the National Guard had 19 observation squadrons. The Depression put an end to the activation of new flying units, but several more would be organized just before the U.S. entered World War II. By the summer of 1940, World War II was raging.