The National Guard's origins trace back to the militia of the first settlements in America. Since its inception in 1636, the National Guard has played vital role in the nation's defense from the Revolutionary War to the most recent conflicts in Iraq and Afghanistan. The utility of the National Guard has been questioned since the late nineteenth century, but political pressure from the states has always been sufficient to maintain a National Guard. This monograph examines the National Guard's performance as the primary source for state volunteers in the Spanish-American War and Philippine Insurrection 1898-1899. While the Regular Army generally viewed the National Guard as less professional and incapable of defending the nation, the results from the National Guard's preparation for the Philippines supported the Regular Army's disdain for them and seemed to indicate a likelihood of failure in combat. However, actual results from the Philippines lead to a different conclusion about the National Guard. This conclusion supports the National Guard as an operational force instead of the strategic reserve as they had been used since World War II. This change in the National Guard's employment is even more critical because of the economic and security challenges the nation faces.