Militias in Missouri date back to the French and Spanish colonial era. There were three different types of early militia: regular, volunteer, and uniformed. The regular militia of the late eighteenth and early nineteenth centuries was compulsory. Only able-bodied men were permitted to serve; the mustering officer decided who to reject from the unit. The volunteer militia of the same era consisted of special units of volunteers and draftees. Members of the uniformed militia had prior service or some form of advanced training.
These early colonial, territorial, and state militias fought in skirmishes and larger conflicts such as the War of 1812, Black Hawk War, Heatherly War, and the Osage War of 1837. During the Mormon and Iowa Wars of the 1830s, the Missouri militia was confronted by highly trained, well-equipped, and well-organized opponents. In the 1840s the volunteer militia fought in the Mexican War and was called upon to serve during periods of social unrest. By 1847, regular and volunteer militias had been disbanded, and only the uniformed militia remained.
Divided loyalties during the Civil War transformed the Missouri militia. The Missouri State Guard, organized in 1861, was sympathetic to the Confederacy. The volunteer Unionist Home Guard formed in opposition to the State Guard. Subsequently, after the Home Guard was disbanded, the Missouri State Militia formed in 1862 as a full-time force. It was augmented by the Enrolled Missouri Militia, which was created as a part-time local defense force consisting of all able-bodied men not already serving in the military.
After the Civil War, in response to social unrest, companies of uniformed militia were reestablished. In 1877 a new militia law declared that the militia would from then on be called the "National Guard of Missouri." At the time, the terms "National Guard" and "Organized Militia" were synonymous. Many more years passed before the National Guard as we now know it began to take form.
In 1898 the militia mobilized in response to the Spanish-American War. After the conflict ended, Congress passed the National Defense Acts of 1903 and 1908. These acts transformed the militia into the present-day National Guard, shifting control from the state level to the federal level, standardizing requirements for admission and training, and providing federal funding to the Guard. In 1916 the National Guard reorganized again, establishing further professionalization and instituting additional federal regulation.
As the twentieth century progressed, the National Guard was involved in major overseas conflicts. In World War I, the Missouri National Guard fought primarily with the Thirty-Fifth Division in France; in World War II, Guard members served in both Europe and the Pacific. Following World War II the Missouri National Guard reorganized, while the Air National Guard was established in 1947. During the Korean War some Missouri Guard units were mobilized. Guard personnel supported the Missouri State Highway Patrol during the 1954 Missouri State Penitentiary riot and again in 1968 when rioting broke out in Kansas City. Individual Missouri Guardsmen participated in Vietnam, and entire units reported for Operation Just Cause (Panama, 1989) and Operation Desert Storm (Iraq, 1991). Guard members served in Kosovo, the Sinai Peninsula, and Afghanistan during the next two decades.
On the domestic front, the Missouri National Guard is routinely called upon for state emergency duty in the event of weather emergencies, hazardous material incidents, manhunts, or to support law enforcement during times of civil unrest. In recent decades, the Guard mobilized for emergency duty during the flood of 1993 and assisted with domestic security in the aftermath of the September 11, 2001, terrorist attacks. Most recently, the Guard was called upon in 2014 to assist law enforcement during the protests in Ferguson, Missouri, after the fatal shooting of Michael Brown by a Ferguson police officer.
—Developed with input from Orval L. Henderson Jr.