The Tennessee State Guard had it's beginning during the Revolutionary War, when volunteers were sought from Sullivan and Washington Counties to fight General Cornwallis in his drive through North Carolina. Some four hundred volunteers crossed the mountains to fight the British. The all-volunteer force was so effective and wreaked such havoc on the British troops, Cornwallis made the threat that if the Tennesseans did not desist from their opposition to the King, the British Army would march over the mountains to lay waste to the land with "fire and Sword," and hang their leaders.

In response to that threat over one-thousand more volunteers came forth to defeat the British at the Battle of King's Mountain. This was on October 7, 1780 and was the birth of the spirit of volunteerism in Tennessee. It wasn't until the War of 1812 that the term, "Volunteer State" was first used, but the spirit was indeed born during the Revolution. During the War of 1812 volunteers from Tennessee once again answered the call of service by serving with the State Militia until Tennessee General Andrew Jackson was asked to take charge of all Federal forces in an effort to stop the British from taking New Orleans. During the Battle of Horseshoe Bend the Tennesseans won a great victory over the "Redstick" group of renegade Indians that had been terrorizing the frontier, and then followed "Gen'l Andy" to New Orleans where they defeated the British in a decisive victory.

A small band of volunteers from Tennessee jumped into the fray to assist Texas in gaining their independence from Mexico. Col. David Crockett and several volunteers traveled the long journey only to end up at a little mission in San Antonio, Texas, better known as the Alamo. After several days of delaying the Mexican Army to protect and allow a fellow Tennessean - Sam Houston, to reorganize the Army of the Republic of Texas, they were all killed.

The title, "Volunteer State," was forever formalized during the Mexican War in the late 1840's when native Tennessean, President James K. Polk requested the state provide one regiment of Cavalry and two of Infantry, but more than tenfold volunteered.

Although split by regional differences, the spirit of volunteerism continued throughout the War Between the States. Tennessee was the location of the second most number of battles and conflicts of the war. Many Confederate units and Union units were volunteers. Three regiments of State Guard were the first to answer the call of the Confederacy to defend Virginia . They were engaged in all actions of the Army of Northern Virginia including the Battle of Gettysburg and remained in that command until the end of the war on 9 April 1865 at Appomattox Courthouse, Virginia. Numerous Union units operated within the central and east Tennessee area of operations and were instrumental during reconstruction.

During the Spanish American War of 1898 the state was once again called upon for volunteers. Four regiments from Tennessee were mustered into service and Tennessee had the only state unit in the nation to stay on and serve during the Philippine Insurrection. They served so valiantly that thirty years later, Army Chief of Staff Summerall reminisced that, "I can say deliberately that the Tennessee Battalion of the 37th U.S. Infantry Regiment are the best soldiers I have ever known, and it is an honor to have been associated with them."

The honor of volunteering was repeated during the First World War. Seven Regiments of State troops were mustered into service forming the nucleus of the 30th Infantry Division. More Medal of Honor awards were made to the men of the 30th than any other unit during WWI. One Medal of Honor recipient, although not a member of the famous 30th Division was the most decorated enlisted man of the war - Tennessee's Sergeant Alvin C. York.

The 30th Division was again called on for duty in February 1941 and subsequently took part in the invasion of Normandy. The 30th spearheaded the breakthrough at St. Lo and was one of the first divisions to break through the Siegfried Line, and at Avranches it held off five German divisions. They gave the Germans such a mauling at the Battle of the Bulge, that the German High Command named them Roosevelt's Shock Troops. This unit's nickname "Old Hickory Division" continues today through the Second Infantry Brigade of the Tennessee State Guard's "Old Hickory Brigade." During WWII the National Guard was federalized and the Tennessee State Guard was organized as a replacement military force in 1941. The State Guard assisted local authorities in securing Dams, railways, and other vital installations during the war. The very law that created them also deactivated them in 1947.

With ever increasing federalization of National Guards across America, many Governors and State Legislatures have realized that in the event of a National emergency, the troops providing local service would be withdrawn from their command. Thus, in 1985 the Tennessee Defense Force was formed to provide a trained and organized military reserve force under the control of the Governor. This force would provide service to the state when the National Guard was under Federal Control or otherwise on a mission for the Governor and unable to perform certain duties to meet the needs of the people.

In 1998 the Legislature of the State of Tennessee changed the name to Tennessee State Guard.