Question: The Battle of Blanco Canyon was the decisive battle of Col. Ranald S. Mackenzie's initial campaign against the Comanche in West Texas, and marked the first time the Comanches had been attacked in the heart of their homeland, Mackenzie, also called Bad Hand, was a career United States Army officer and general in the Union Army during which event?
Context: John Fulton Reynolds (September 20, 1820 – July 1, 1863) was a career United States Army officer and a general in the American Civil War.  One of the Union Army's most respected senior commanders, he played a key role in committing the Army of the Potomac to the Battle of Gettysburg and was killed at the start of the battle. Jose Piedad Tafoya (1834 - ca. 1913), sometimes called the Prince of the Comancheros, was one of the more notable traders from New Mexico who traveled throughout the Southern Great Plains exchanging goods with the Comanches and their allies the Kiowa for stolen horses, cattle, and sometimes human captives.  According to legend, he was seven feet tall.  He was born in La Cuesta, New Mexico in 1834 and first visited the Great Plains as early as 1859.  In the 1850s, he operated a sheep ranch in San Miguel County, New Mexico.  His first wife was Maria de Jesus Perez.  They married April 20, 1863 in Anton Chico, New Mexico.  In the 1860s, he operated a trading post near what is now Quitaque, Texas.  In the 1870s, he began sheep herding in Texas.  He also at times acted as a scout for the US Army, possibly unwillingly.  According to some sources, he was instrumental in the defeat of the Comanches at the Battle of Palo Duro Canyon.  He allegedly revealed the location of Comanche camps to Colonel Ranald S. Mackenzie after being forced to do so either at the end of a rope or after being tied to a wagon wheel.  Some believe that this story is mythical.  Mackenzie credited another Comanchero scout named Johnson for finding the camps.  Tafoya also participated in the ill-fated Buffalo Soldier tragedy of 1877.  In 1879, he accompanied Lt. John L. Bullis on an expedition into southern New Mexico in pursuit of a band of marauding Lipan and Mescalero Apaches. By the 1880s, he had left Texas and was once again ranching sheep in New Mexico.  He appeared in the U.S. Court of Claims in 1893 along with three other former Comancheros, where they admitted to having purchased cattle marked with brands belonging to Charles Goodnight and others.  He had at least four children and probably died about 1913, when his will was filed, bequeathing his house to his second wife, Teresa Baca de Tafoya. The Battle of Little Robe Creek, also called the Battle of Antelope Hills, took place on May 12, 1858.  It actually was a series of three distinct encounters that took place on a single day, between the Comanches on the one side, and Texas Rangers, militia, and allied Tonkawas attacking them.  It was undertaken against the laws of the United States at the time, which strictly forbade such an incursion into the Indian Territories of Oklahoma, and marked a significant escalation of the Indian Wars.  It also marked the first time American or Texas Ranger forces had penetrated the Comancheria as far as the Wichita Mountains, and Canadian River, and it marked a decisive defeat for the Comanches. The Warren Wagon Train raid, also known as the Salt Creek massacre, occurred on May 18, 1871.  Henry Warren was contracted to haul supplies to forts in the west of Texas, including Fort Richardson, Fort Griffin, and Fort Concho.  Traveling down the Jacksboro-Belknap road heading towards Salt Creek Crossing, they encountered William Tecumseh Sherman.  Less than an hour after encountering the famous General, they spotted a rather large group of riders ahead.  They quickly realized that these were Native American warriors, probably Kiowa and/or Comanche.  The corn train quickly shifted into a ring formation, and all the mules were put into the center of the ring.  The warriors destroyed the corn supplies, killing and mutilating seven of the wagoneer's bodies.  Five men managed to escape, one of which was Thomas Brazeale who reached Fort Richardson on foot, some 20 miles away.  As soon as Col. Ranald S. Mackenzie learned of the incident, he informed Sherman.  Sherman and Mackenzie searched for the warriors responsible for the raid.  In the end, notwithstanding the intervention of Guipago (Lone Wolf), well equipped with loaded rifles and revolvers and ready to fight, 3 of the war leaders involved were arrested at Fort Sill: Satanta (White Bear), Satank (Sitting Bear), and Ado-ete (Big Tree).  Satank attempted to escape and was killed while traveling to Fort Richardson for trial.  The other two were tried and convicted of murder. James Birdseye McPherson (November 14, 1828 – July 22, 1864) was a career United States Army officer who served as a general in the Union Army during the American Civil War.  McPherson was on the General's staff of Henry Halleck and later, of Ulysses S. Grant and was with Grant at the Battle of Shiloh.  He was killed at the Battle of Atlanta, facing the army of his old West Point classmate John Bell Hood, who paid a warm tribute to his character.  He was the second highest ranking Union officer killed during the war. The Battle of Palo Duro Canyon was a military confrontation and a significant United States victory during the Red River War.  The battle occurred on September 28, 1874 when several U.S. Army regiments under Ranald S. Mackenzie attacked a large encampment of Plains Indians in Palo Duro Canyon in the Texas Panhandle. William Henry French (January 13, 1815 – May 20, 1881) was a career United States Army officer and a Union Army General in the American Civil War.  He rose to temporarily command a corps within the Army of the Potomac, but was relieved of active field duty following poor performance by his command during the Mine Run Campaign in late 1863.  He remained in the Army and went on to command several Army installations before his retirement in 1880. The Battle of North Fork or the Battle of the North Fork of the Red River occurred on September 28, 1872, near McClellan Creek in Gray County, Texas, United States.  A monument on that spot marks the site of the battle between the Comanche Indians under Kai-Wotche and Mow-way and a detachment of cavalry and scouts under U.S. Army Colonel Ranald S. Mackenzie.  There was an accusation that the battle was really an attempt "to make a massacre," as during the height of battle some noncombatants were wounded while mixed in with warriors. The Battle of Blanco Canyon was the decisive battle of Col. Ranald S. Mackenzie's initial campaign against the Comanche in West Texas, and marked the first time the Comanches had been attacked in the heart of their homeland.  It was also the first time a large military force explored the heart of Comancheria.  On 12 August 1871 Mackenzie and Colonel Benjamin Grierson were asked by Indian Agent Lawrie Tatum to begin an expedition against the Kotsoteka and Quahadi Comanche bands, both of whom had refused to relocate onto a reservation after the Warren Wagon Train Raid.  Col. Mackenzie assembled a powerful force consisting of eight companies of the Fourth United States Cavalry, two companies of the Eleventh Infantry, and a group of twenty Tonkawa scouts. Ranald Slidell Mackenzie, also called Bad Hand, (July 27, 1840 – January 19, 1889) was a career United States Army officer and general in the Union Army during the American Civil War.  He was described by General Ulysses S. Grant as its most promising young officer.  He also served with great distinction in the following Indian Wars.
Answer: American Civil War