Bullis enlisted as a corporal in the 126th New York Volunteer Infantry on August 8, 1862, and subsequently participated in several of the most important actions of the Civil War. At the battle of Harper's Ferry in September 1862 he was wounded and captured. He rejoined his regiment after exchange, was again wounded and captured at the battle of Gettysburg, and spent the following ten months confined to the notorious Libby Prison in Virginia. Having again been exchanged for Confederate prisoners in the spring of 1864, he joined the 118th United States Infantry, Colored, and received the rank of captain. He participated in a number of major combats around Richmond, Virginia, during the remaining months of the war.
Bullis reenlisted in the regular army as a second lieutenant on September 3, 1867, and returned to Texas, where his Civil War regiment had been stationed for Reconstruction duty following the war's end. Garrison assignments in coastal Texas provided little chance for military action or promotion, and so in November 1869 he was transferred by request to the new Twenty-fourth Infantry, composed of white officers and black enlisted men. Although the initial years of service along the lower Rio Grande border proved fairly routine, Bullis participated in a number of operations against small Indian raiding parties and cattle rustlers. More important, while stationed at Fort Clark in 1873, he received command of a special troop of Black Seminole scouts that had been mustered three years earlier. Because of their intimate knowledge of the terrain in Coahuila, Mexico, the scouts were assigned to Col. Ranald S. Mackenzie's expedition in 1873 against renegade Kickapoo camps at Remolino. Bullis and his twenty scouts distinguished themselves in battle and played an important role in Mackenzie's withdrawal to Texas. They served again with Mackenzie during the Red River War of 1874, which was directed against Comanches, Kiowas, and Southern Cheyennes in the Texas Panhandle. Sixteen years later Bullis received brevet citations for his "gallant service" at Remolino, for similar actions on the Pecos River and near Saragosa, Mexico, during 1875 and 1876 respectively, and for a fight in 1881 with Lipan Apaches at the Burro Mountains in Coahuila.
Upon Bullis's transfer in 1882 from command of the Black Seminole scouts to new duties in Indian Territory, the people of Kinney County, Texas, presented him with two ceremonial swords, one silver and one gold, in appreciation of his efforts to protect the border. The swords were later donated by his daughters to the Witte Museum in San Antonio. The Texas legislature likewise passed a special resolution in his honor. After service at Camp Supply in Indian Territory from 1882 to 1888, Bullis joined his old regiment in Arizona and served as agent for the Apaches at San Carlos Reservation. In 1893 he was transferred to Santa Fe, New Mexico Territory, to act as agent for the Pueblos and Jicarilla Apaches. Four years later he returned to Texas with the rank of major and was appointed paymaster at Fort Sam Houston. During the Spanish-American War and Philippine Insurrection he saw service in Cuba and the Philippines. In 1904 President Theodore Roosevelt promoted him to the rank of brigadier general, and on the following day Bullis retired from service.
Drawing upon knowledge from his scouting experiences across West Texas, Bullis purchased numerous tracts of land as investments. In 1885 he also entered into a lucrative partnership with fellow officer William R. Shafter and rancher John W. Spencer to open the Shafter silver mines in Presidio County. The investments made Bullis a wealthy man and helped promote the settlement of West Texas. His marriage in 1872 to Alice Rodríguez of San Antonio ended with her death in 1887. Four years later he married Josephine Withers, also of San Antonio; they had three daughters. Bullis died in San Antonio on May 26, 1911. He received a final, posthumous, honor when, on the eve of American entry into World War I, the new military training base near San Antonio was named Camp Bullis.
29° 25.292, -098° 27.997
San Antonio National Cemetery