Historically.... 

American Indians have participated with distinction in United States military actions for more than 200 years.

        United States military service provides an outlet for young Native Americans to fulfill a cultural purpose rooted in tradition -- to fight and defend their homeland. Native Americans' courage, determination, and fighting spirit were recognized by American military leaders as early as the 18th century.

I think they [Indians] can be made of excellent use, as scouts and light troops.             --Gen. George Washington, 1778

         Many tribes were involved in the War of 1812, and Indians fought for both sides as auxiliary troops in the Civil War. The earliest recorded date of Native Americans becoming U.S. citizens was in 1831 when the Mississippi Choctaw became citizens after the ratification of the Treaty of Dancing Rabbit Creek. However, it wasn't until The Indian Citizenship Act of 1924, that U.S. citizenship was granted entirely to America's indigenous peoples, called "Indians" in this Act.

Native Americans as Scouts... 

         Scouting the enemy was recognized as a particular skill of the Native American soldier. In 1866, the U.S. Army established its Indian Scouts to exploit this aptitude. The Scouts were active in the American West in the late 1800s and early 1900s, accompanying Gen. John J. Pershing's expedition to Mexico in pursuit of Pancho Villa in 1916. They were deactivated in 1947 when their last member retired from the Army in ceremonies at Ft. Huachuca, Arizona. Native Americans from Indian Territory were also recruited by Teddy Roosevelt's Rough Riders and saw action in Cuba in the Spanish-American War in 1898. As the military entered the 20th century, American Indians had already made a substantial contribution through military service and were on the brink of playing an even larger role.

Native Americans in WWI & WWII... 

          It is estimated that more than 12,000 American Indians served in the United States military in World War I. Approximately 600 Oklahoma Indians, mostly Chotaw and Cherokee, were assigned to the 142nd Infantry of the 36th Texas-Oklahoma National Guard Division. The 142nd saw action in France and its soldiers were widely recognized for their contributions in battle. Four men from this unit were awarded the Croix de Guerre, while others received the Church War Cross for gallantry.

Battle-experienced American Indian troops from World War II were joined by newly recruited Native Americans to fight Communist aggression during the Korean conflict. The Native American's strong sense of patriotism and courage emerged once again during the Vietnam era. More than 42,000 Native Americans, more than 90 percent of them volunteers, fought in Vietnam. Native American contributions in United States military combat continued in the 1980s and 1990s as they saw duty in Grenada, Panama, Somalia, and the Persian Gulf.

          There were reportedly 190,00 Native American military veterans at the close of the 20th Century.

Native Americans as Warriors....

To be an American Indian warrior is to have physical, mental, and spiritual strength. A warrior must be prepared to overpower the enemy and face death head-on.

We honor our veterans for their bravery and because by seeing death on the battlefield, they truly know the greatness of life. --Winnebago Elder

27221A - Lt. Ernest Childers, a Creek, being congratulated by Gen. Jacob L. Devers after receiving the Congressional Medal of Honor in Italy for wiping out two machine-gun nests. U.S. Army Signal Corps photograph, July 13, 1944 WWII activities.

Related resources:

American Indian Medal of Honor Winners
Indians in the War [World War II]
Navajo Code Talkers in World War II: A Bibliography
Navajo Code Talker Fact Sheet
Navajo Code Talker Dictionary
Reminiscences of Seattle...Sloop of War Decatur During the Indian War of 1855-56

The Old West:

W25575 - Column of Cavalry, artillery and wagons commanded by General George A. Custer, crossing the plains of Dakota Territory. By W.H.Illingworth, 1874 Black Hills Expedition.

W25587B - Troop "C' 5th Cavalry, which arrested boomers and squatters prior to the opening of Oklahoma, 1888.