Both the National Guard and the various state defense forces trace their roots to organized militia units which composed the majority of American military forces before the creation of the modern National Guard under the Militia Act of 1903.

Following the American entrance into World War II and federalization of all National Guard units, numerous states created state defense forces in order to protect their territory against invasion, unrest, insurrection, and sabotage while their National Guard units were deployed.

[2] In April 1943, the Nebraska State Guard was deployed alongside federal Army soldiers and civilian volunteers to assist in protecting the Omaha Municipal Airport from floodwater during a flood of the Missouri River.

[4] Due to the heightened chance of deployment for several National Guard units chosen to be a part of the Selected Reserve Force during the Vietnam War, Governor Norbert T. Tiemann reactivated Nebraska's state defense force in 1968 to replace the Nebraska National Guard.

The Nebraska State Guard was organized at a cadre level, with plans to expand through four phases and ultimately reach a full strength of roughly 4,000 men; however, due to the repeal of the Selected Reserve Force program, the Vietnam-era State Guard never expanded beyond a cadre of approximately 220 officers and enlisted men, primarily veterans of World War II or the Vietnam War, organized across 35 units in 30 towns.