Adna Romanza Chaffee, army officer, son of Truman Bibbins and Grace (Hyde) Chaffee, was born on April 14, 1842, in Orwell, Ohio, and educated at a nearby country school. He joined the regular Sixth Cavalry on July 22, 1861, and saw action in the Peninsular campaign, the battle of Antietam, the battle of Fredericksburg, the Stoneman Raid, and the battle of Gettysburg, where he was wounded and narrowly escaped capture. Throughout 1864 he took part in Gen. Philip Sheridan's Virginia campaigns and was promoted to first lieutenant in February 1865.
After the Sixth Cavalry's reorganization in the summer of 1865, Chaffee was transferred to Austin, Texas, where he was appointed depot quartermaster on December 12, 1866. In March 1867 he resigned his commission with thoughts of going into business, but was persuaded to seek restoration to rank. After promotion to captain in October, he was assigned in February 1868 to Fort Griffin. On March 5 he successfully pursued a band of Quahadi Comanche warriors who had attacked a wagon train hauling lumber from the Mill Creek sawmill. Chaffee and his men found the Quahadis taking refuge near Paint Creek, encircled the camp, charged, and defeated them. Chaffee was brevetted a major for his actions. With his reputation as an Indian fighter established, he spent the next three years at various army camps in Texas chasing down outlaws and hostile Indians. The dogged persistence of Chaffee and his men on the Texas frontier soon gained them the name Chaffee's Guerillas.
Chaffee was transferred to Fort Riley, Kansas, in March 1871 and spent most of 1872 on detached duty at Oxford, Mississippi. After returning to Kansas, he was stationed briefly at Fort Harker and in April 1873 moved to Camp Supply, Indian Territory, in response to increased tension caused by hide hunters entering the southern plains. When the Red River War broke out in 1874, Chaffee was attached to Col. Nelson A. Miles's column, and on August 30 in Palo Duro Canyon his command was among the Sixth Cavalry forces in the front lines. With his famous exhortation, "Forward; if any man is killed I will make him a corporal!" Chaffee led his troops in a charge against a superior number of Cheyenne warriors, whom the cavalry then chased as far west as what is now Randall County. Chaffee was subsequently brevetted a lieutenant colonel. On October 14 he led a force against a hostile Indian camp located between Gageby and Sweetwater creeks. On March 31, 1875, he married Annie Frances Rockwell; they had three daughters and a son.
For a decade beginning in 1875 Chaffee and his command responded to troubles with the Apaches at Fort Verde, Arizona. He commanded the garrison in 1878, served as agent at the San Carlos Reservation in 1879–80, and participated in Gen. George Crook's expedition in 1883. He was transferred in 1884 to New Mexico and was at Fort Wingate when Geronimo and his Chiricahua Apache followers broke out of their reservation in 1885. Chaffee remained in southern Arizona and New Mexico until the chief surrendered in September 1886.
On July 7, 1888, with the Indian depredations at an end, he was promoted to major in the regular army and transferred to the Ninth Cavalry. For the next two years he supervised the construction of Fort Duchesne in southern Utah. He served as acting inspector general for the Department of Arizona from 1890 to 1893 and for the Department of Colorado until the fall of 1894. Chaffee then moved to Fort Robinson, Nebraska, and in 1895 conducted the restoration of the Bannock Indians to the Fort Hall reservation in Idaho. He served as an instructor at the Infantry and Cavalry School at Fort Leavenworth, Kansas, from November 1896 to June 1897, when he was appointed lieutenant colonel of the Third Cavalry.
With the outbreak of the Spanish-American War, Chaffee was made brigadier general (in May 1898) and commanded the Third Brigade of Gen. Henry W. Lawton's Second Division volunteers in Cuba. As a result of his performance in the capture of El Caney on July 1, he was promoted to major general. After a brief respite he returned to Cuba in December 1898, as chief of staff of the military government under Gen. Leonard Wood, a post he held until May 1900. Having lost his volunteer rank in reduction of the army, Chaffee was again appointed brigadier general of volunteers in April 1889 and then promoted to colonel in the regular United States Army in May 1899.
In July 1900 he was reappointed major general of volunteers and given command of the 2,500-man United States contingent in the joint relief expedition sent to put down the Boxer Rebellion in China. His troops took the gates of Peking on August 14, 1900, and relieved the city's besieged embassies. The success of that mission made Chaffee a celebrity among the troops and commanders as well as the Chinese. After his advancement to major general in February 1901, Chaffee was appointed military governor and commander of the United States forces in the Philippines, where he remained until October 1902. He commanded the Department of the East until October 1903; he helped organize the General Staff Corps and in January 1904 was named United States Army Chief of Staff, with the rank of lieutenant general. He served as grand marshal for President Theodore Roosevelt's inaugural parade on March 4, 1905, in which former Indian adversaries like Geronimo and Quanah Parker also participated. Afterward, he went on a good-will tour of Europe on behalf of the president. Chaffee stepped down from his position on January 15, 1906, and retired from the army two weeks later. He was subsequently named a member of the Board of Visitors of West Point. Later he and his wife moved to Los Angeles, California, where he served as chairman of that city's Board of Public Works and as first president of the Southwest Museum. Chaffee died of typhoid pneumonia on November 1, 1914, and was interred in Arlington National Cemetery.