Founded in 1636 as a citizen force, the U.S. National Guard is a “ready” reserve group of 450,000 men and women voluntarily serving in all 50 states and four U.S. territories. Guard members hold civilian jobs and maintain part-time military training. They are called to service in times of civil unrest, natural disasters, labor strikes, wars, health emergencies and riots.

Uniquely existing as both a state and federal force, as per the U.S. Constitution, Guard units may be called on to preserve public safety, order and peace at home in times of emergency and may also be deployed to serve as essential parts of America’s forces abroad.

“The National Guard stands separate and distinct from the other federal reserve forces of the Army, Navy, Air Force and Marines,” writes Michael Doubler in I Am The Guard: A History of the Army National Guard. “National Guard troops serve at the direction of the state governors until the U.S. president orders them to active federal service for either domestic emergencies or overseas service.”

Guard soldiers typically serve in their home states, living at home and usually holding private-sector jobs, with drills scheduled for one weekend a month and an annual two-week training program.

Evolving over nearly 400 years from local Colonial militias to fighting the first American Revolution battles, to serving in two world wars, to securing the U.S. capitol from a rioting mob in 2021, the National Guard serves on the community and country levels, responding to combat and reconstruction missions, domestic emergencies and more and has participated in every major U.S. conflict.

Pre-dating the U.S. Army, the Army National Guard, the nation’s first organized fighting force, originated on December 13, 1636, in the Massachusetts Bay Colony, when three militia regiments were formed to defend against members of the Pequot Tribe and provide security and structure for the early settlements. Men between the ages of 16 and 60 were required to join, and the original three Massachusetts regiments continue to operate today.

“In the absence of military assistance from Great Britain, the militia system alone guaranteed the success of early English colonization,” Doubler writes. “As the Indian threat receded, militiamen found themselves more and more engaged against other colonial powers. Battles against the Spanish and French and service alongside British Regulars often revealed the militia’s best and worst aspects. By the late 1700s, the militia was a bulwark against unwelcome British intrusion into colonial affairs.”

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During the American Revolution, the units gained the name Minutemen, a nod to their quick response time, as they fought the first battles of the war. The militias also formed volunteer armies during the Civil War and offered protection to settlers during westward expansion, Doubler adds. The Militia Act of 1903, also known as the Dick Act, created the building blocks of the modern National Guard, allowing for more federal support and control.

The Guard’s first aviation unit was established on November 1, 1915, and, three decades later, on September 18, 1947, with the creation of the Air Force, the Air National Guard was formed. Since then, members of the Air Guard have seen combat in the Korean and Vietnam wars, Persian Gulf crisis, 9/11 terrorist attacks, hurricane relief efforts, the war in Afghanistan and other operations.

Following the sinking of the Lusitania on May 7, 1915, Congress passed, and President Woodrow Wilson signed into law, the National Defense Act of 1916, which made significant changes to the organization, including giving it the official name of National Guard, increasing and standardizing training, adding funding, administering annual inspections and requiring the passage of fitness and eligibility tests.

"The law codified the dual state and federal mission of the National Guard and required new Guardsmen to swear allegiance to both the Constitution of the United States and their state of record," the Guard notes. "The president of the United States could now federalize the National Guard in time of declared federal emergency and provided for expeditionary service."

After the United States entered World War I, Harry S. Truman, as a captain in the Missouri National Guard, fought in Argonne, France in 1918 with the U.S. First Army. During that conflict, Harlem’s celebrated Hellfighters, a group of black guardsmen who fought as the 369th Infantry Regiment, were given the Croix de Guerre French military decoration for their heroism.

In September 1940, with America’s entry into World War II on the horizon, President Franklin D. Roosevelt called up the National Guard for a year of training. “The federalization of the Guard doubled the size of America’s active duty forces,” the USO reports. “That, combined with the institution of America’s first peacetime draft, provided the manpower for America’s eventual intervention in Europe.”

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Today, only the U.S. Army boasts more members than the National Guard, and while 10 presidents, including George Washington, Thomas Jefferson and Abraham Lincoln, were part of state militias, Harry S. Truman (Missouri Army National Guard) and George W. Bush (Texas Air National Guard) are the only two presidents who served in the branch in modern times.

The National Guard has been activated on U.S. soil at least 16 times at the federal level, including the Civil War from 1861-65, the desegregation of Central High School in Little Rock, Arkansas from 1957-58, the march from Selma to Montgomery, Alabama in 1965, the Cuban Refugee Crisis in 1980 and the Los Angeles Riots in 1992.

Since the September 11, 2001 terrorist attacks, the National Guard has mobilized more than 500,000 soldiers for federal missions, according to the Guard, and, in its state role, has played an important part in disaster relief and homeland defense. During Hurricane Katrina in 2005, about 50,000 National Guard troops were deployed to the Gulf Coast for humanitarian, evacuation and relief operations.

More recently, in 2020, almost 100,000 Guard members were deployed as assistance for the coronavirus pandemic, California wildfires and anti-racism protests. On January 6, 2021, the day Congress was gathered to officially count the Electoral College vote, Guard members were called upon after a mob breached the U.S. Capitol.