The 11th U.S. Cavalry was activated by Congress on 2 February 1901 at Fort Myer, Virginia. New recruits had to be able to read, write, and be mentally and physically fit. These were high standards for the time. Not everyone was cut out to be in the Cavalry.

In December 1901, the Regiment was deployed to the jungles of the Philippines. Its mission was to help neutralize insurrectionist forces trying to seize power. For this tropical deployment, the men operated more like light infantry than cavalry, due to the jungle terrain in which they fought and patrolled. In addition to their Krag-Jorgensen rifles, the men were issued "bolo" knives - machetes used in the Philippines to slash through thick vegetation. The bolos became a part of the Blackhorse crest. First Squadron saw the heaviest action in the Samar campaign of 1902 for which it earned the Regiment's first battle streamer, embroidered "Samar 1902." It was also there that the Regiment suffered its first trooper killed in action: Private Clarence L. Gibbs, who was shot 4 March 1902, by guerrilla forces who ambushed a U.S. wagon train.

The Regiment returned to the U.S. on 12 March 1904. By 1905, the entire Regiment was for the first time in its history stationed at one installation - Fort Des Moines, Iowa. It was there that the Regiment received its next mission abroad, to Cuba. The Regiment (less First Squadron which remained at Fort Des Moines) deployed to Cuba on 16 October 1906 as part of President Theodore Roosevelt's army of pacification. Its mission was to show the American flag by conducting small mounted patrols throughout the island. By February 1909, the Cuban situation was calm and the 11th Cavalry returned to the U.S. rewarded for its service by marching in President William Taft's inaugural parade in Washington, DC.

In March 1909, the Regiment was stationed at Fort Oglethorpe, Georgia. While there, its mission was training, but it was interrupted at least three times for missions elsewhere. In early 1911, when the situation in Mexico worsened, the Regiment was ordered to Fort Sam Houston, Texas, to train for a possible deployment into Mexico, but by November, the situation eased again and the 11th Cavalry returned to Georgia. In May 1914, a domestic crisis arose in a Colorado mining community. The incident was dubbed "The Ludlow Massacre" and it touched off an armed riot. The Colorado militia was unable to halt it, so the President deployed the 11th US Cavalry to the towns of Trinidad and Ludlow, Colorado, to stop the bloodshed by disarming the aggressors. The Regiment was successful and returned to Fort Oglethorpe in January 1915. Upon the Regiment's return to Fort Oglethorpe, the situation in Mexico was worsening again.

One particular rebel leader there, Francisco "Pancho" Villa, was becoming bolder in his struggle to win supporters for his own power. Villa had formerly been an ally of the man whom the US government recognized as the legitimate President of Mexico, Venustiano Carranza; but he was now his bitter enemy, and sought to seize power from him. Because of the long standing tension between U.S. border towns and Mexico, a popular tactic used by the Mexican rebels was to attack US property or persons a show of power and boldness that would draw Mexican supporters to their cause. Villa did just that. On 9 March 1916, his forces raided the town of Columbus, New Mexico, killing fifteen Americans and leaving the town in ruins. The assault could not be ignored. President Woodrow Wilson immediately ordered General John J. Pershing to lead a punitive expedition into Mexico to capture Villa and neutralize his army. On 12 March 1916, the 11th Cavalry received orders to join Pershing's expedition.

It was in Mexico, on 5 May 1916, that the Second Squadron (Provisional), 11th US Cavalry, commanded by Major Robert L. Howze, led the last mounted cavalry charge in U.S. history. The squadron was moving northward from its camp in Parol, Mexico. Upon reaching the town of Ojo Azules, Howze's force was surprised by a band of Villa's men. A two hour gun fight ensued. When it was over, Howze's men counted forty-two enemy dead and many wounded. There were no friendly casualties. The incident would later be known in history as the "Last Mounted Charge."

May 5th is the Regiment's official Organization Day, in honor of Howze's charge. The Regiment remained in the United States during World War I (1914 - 1918). On 9 July 1919, it moved from the eastern US to its new post, the Presidio of Monterey, California. Its new mission was to patrol the US / Mexico border. These were relatively quiet years for the Regiment.

Regimental historians believe it was in Monterey that the Regiment received its nickname "Blackhorse." One tragic disturbance began on 14 September 1924 - "The Great Monterey Oil Fire." It erupted when lightning struck an oil storage tank near the post. Massive explosions occurred shortly after and a fire spread to nearby storage tanks and property. The fire raged for five days. The entire 11th Cavalry participated in the fire fighting effort. Twenty-six Blackhorse troopers were killed. In 1929, the Regiment appeared in the Hollywood film "Troopers Three" as background extras. In 1937, the Regiment appeared in the Ronald Reagan film "Sergeant Murphy," and on 1 June participated in the opening ceremony of the Golden Gate Bridge.

World War I taught military planners that the dynamics of modern battle were pushing the horse into obsolescence. In the 1930's the 11th Cavalry was ordered to start experimenting with scout cars, the first mechanized cavalry vehicles. Few cavalrymen, if any, wanted to give up their trusted horses. An era had come to an end.

On 15 July 1942, the 11th US Cavalry was inactivated at Fort Benning, Georgia. The Headquarters and Headquarters Troop was redesignated on 19 April 1943 as the Headquarters and Headquarters Troop, 11th Cavalry Group Mechanized. The former squadrons of the 11th Cavalry were sent to fight with the 10th Armored Division and the 90th Infantry Division overseas. The new HHT, 11th Cavalry Group Mechanized drew new squadrons, the 36th and 4th, and also received an Assault Gun Troop (a howitzer battery). After guarding the US southeastern coast from March to June 1944, the Group moved to Camp Gordon, Georgia to begin training for an overseas deployment.

The Regiment departed from New York Harbor bound for the United Kingdom on 29 September, arriving on 10 October. The Regiment entered France on 23 November 1944. The first unit of the Blackhorse to cross the English Channel was Troop B, 4th Squadron, commanded by 1LT Leonard B. Holder, who would later become the 37th Colonel of the Regiment. Moving through France and into Germany, the Blackhorse was assigned to the Ninth U.S. Army and attached to the XIII Corps, whose flank the Blackhorse screened during the Corps' sweep from the Roer to the Rhine.

After the war ended, the 11th Cavalry Group Mechanized was redesignated as the 11th Constabulary Regiment on 3 May 1946, and remained in Germany to maintain order in its area of war torn Germany. The Regiment did this until November 1948 when it was redesignated as the 11th Armored Cavalry Regiment and inactivated.

In 1950 war erupted in Korea between communist and democratic factions. On 1 April 1951, the Blackhorse was brought back onto active status as the 11th Armored Cavalry Regiment at Camp Carson, Colorado. In 1954, the Regiment transferred to Fort Knox, Kentucky, the "Home of Armor," to complete its training in fully armored tactics. In mid-March 1957, the entire Regiment rotated to southern Germany to relieve the 6th ACR patrolling the Germany Czechoslovakia border.

In 1960, the Regiment received its first organic aviation asset: the Separate Aviation Company, to assist in surveillance and transport missions. In 1964, the Regiment returned to the United States and was stationed at Fort Meade, Maryland, for two years, until it received orders in March 1966 to deploy to Vietnam.

The Blackhorse arrived in Vietnam on 7 September 1966 (the Air Troop arrived in December). At that time, the Regiment was equipped with M113 Armored Cavalry Assault Vehicles (ACAV) and M48A3 tanks - later the M551 Sheridan was employed. The Air Cavalry Troop as it was now called, or "Air Troop," had a mix of OH-6A scout helicopters, UH-1H Hueys, and later, AH-1 Cobra attack helicopters. In Vietnam the Regiment received its own distinctive patch, won fourteen battle streamers, and had three of its troopers awarded the Medal of Honor.

One of the Regiment's most notable missions began on 1 May 1970 when it spearheaded a US and Army of the Republic of Vietnam joint incursion into Cambodia, a country that was formerly off limits to US forces. There, in Operation Fish Hook, friendly forces surrounded and choked off a huge North Vietnamese logistics center. Enormous amounts of enemy ammunition, equipment, and food were captured.

In February 1971, the Regiment (minus Second Squadron and the Air Troop) redeployed to the US and inactivated. Air Troop and Second Squadron remained in Vietnam attached to other units until they too inactivated in Vietnam on 20 March and 6 April 1972, respectively.

On 17 May 1972, the 14th Armored Cavalry Regiment, which had the mission of patrolling the East-West German border along the Fulda Gap, was redesignated as the 11th Armored Cavalry Regiment in a ceremony at Downs Barracks. In the 1980's, the Regiment underwent several force modernization's, obtaining M1A1 Abrams tanks, M3 Bradley Fighting Vehicles, and UH-60A Blackhawk helicopters. The Regiment also received Heavy Equipment Movement Transport Trucks (HEMTT), High Mobility Multipurpose Wheeled Vehicles (HMMWV), M109A2 Howitzers, and Field Artillery Ammunition Support Vehicles (FAASV).

On 9 November 1989, the East-West German border fell. By December 1991 the Soviet Union dissolved. The Regiment's seventeen year vigil along the Iron Curtain was over. In August 1990, Iraq invaded Kuwait, prompting the U.S. to respond.

First Platoon, E Troop, 2nd Squadron deployed with the 3rd ACR, while the remainder of the Regiment trained Reserve Component Scouts for war at Camp Colt, Germany. On 10 April 1991, the Regiment deployed an Aviation Task Force to support Kurdish relief operations in Turkey and Iraq. On 16 May 1991, remaining Blackhorse units (less Troops B, F, and K) received orders to deploy to Kuwait to secure the country as it struggled to rebuild after the war. On 11 July 1991, an accidental explosion at Blackhorse Base, Doha, shook the Regiment. A fire caused by a faulty heater in a FAASV touched off a chain of blasts. Recovery was swift, but the explosion was not the last set back the Regiment would endure. On 23 July, another accidental explosion during an Explosion Ordnance Detachment (EOD) clean up detail took the lives of three soldiers - two from the EOD and one from the Regimental Headquarters Troop: Private First Class Joshua Fleming.

By October, the Regiment had completed its missions in Turkey and Kuwait and returned to Fulda. As the need for U.S. forces in Europe decreased, the Blackhorse Regiment was inactivated in an emotional ceremony on 15 March 1994.

On October 26, 1994 the 11th U.S. Cavalry was reactivated in the California desert. The mission, to train other U.S. Army units from around the country to be the best in the world. The 11th Cavalry, minus the 3rd squadron, became the top gun of armor tactics and the opposing force to beat in desert battle training at the National Training Center at Fort Irwin, California.

It was not ment to be, that such a famous cavalry unit would be only a memory, or become a portion of itself. So in September of 1995 the remainder of the Blackhorse, the 3rd squadron, was reactivated as the Las Vegas National Guard.