Today In Wyoming's History: August 5, 1917. National Guardsmen Conscripted.

 Mustered Illinois National Guardsmen, August 4, 1917.

From:  Today In Wyoming's History: August 5: 

1917 The entire National Guard, only recently released from duty due to the crisis with Mexico, and then recalled due to the outbreak of World War One, was conscripted into the U.S. Army. The technicality of conscription was necessary due to an Adjutant General's opinion that the National Guard could not serve overseas.

This is an interesting and in some ways curious event.  Unlike mobilizations that would come subsequent to World War One, how exactly to muster the National Guard into Federal Service wasn't entirely clear.  You would think, the Guard having been recently Federalized for border service, that it would have been, but it wasn't.

The real oddity that developed concerned the deployment of Guardsmen overseas.  It had long been presumed that Federalized militia, then being in Federal service, could serve overseas.  Indeed, Federalized militia had served overseas before.  The militia mobilized for the Mexican War served in Mexico, and militia Federalized for the Spanish American War, including those units then called "National Guard" units, had served in both Cuba and the Philippines.  Indeed, National Guard units had fought in the Philippine Insurrection, our first foreign war against guerilla insurgents.

In practical terms there was no earthly way that the United States could even contemplate fighting in France in the Great War without the National Guard.  Quite a few Regular Army officers hated the idea and resentment against the Guard dating back to the late 19th Century was pretty strong.  But the Guard made up about half of the body of men who were armed, uniformed, and at least theoretically prepared to fight.  Moreover, mobilization for Punitive Expedition had sharpened their abilities. They had to go.

Unfortunately for the Wilson Administration, the Adjutant General of the United States Army didn't think they could.  His opinion, a really questionable one at that, was that Guardsmen were only liable for duty in the Continental United States.  This was based on his reading of "Militia Clause" of the United States Constitution, which noted that state militia's cold be called out to "execute the laws of the union, suppress insurrection and repel invasions."  The war with Germany was not, he reasoned, any of those, and therefore the National Guard could only serve domestically.  This problem had to be solved, and easily was, by conscripting them all. . .which occurred on this date in 1917.