Born November 15, 1834, in Carrollton, Illinois. Reno entered West Point Military Academy on September 1, 1851, from Illinois. It took him almost six years to graduate, mostly due to acquiring demerits for being late and tardy. Reno ranked 20th in a class of 38, graduating in June 1857.
Reno commanded the 7th Cavalry during Custer's absence during the winter and early spring of 1876. During this time the full regiment was brought together for the planned campaign against the Sioux and Cheyenne south of the Yellowstone River in southeastern Montana. Custer returned to Fort Abraham Lincoln in early May. Major Reno was second in command of the 7th Cavalry as part of the Dakota Column headed by General Alfred Terry which left Fort Abraham Lincoln on May 17, 1876.
Reno led the scout with six companies of the 7th from June 10-19 discovering that the large Indian village had moved from the Rosebud west to the Bighorn valley. On June 22 the 7th Cavalry Regiment left the Yellowstone River at the mouth of the Rosebud as part of a pincers movement against the Sioux/Cheyenne village.
On June 25th Custer's Crow scouts located the village from the Crow's Nest fifteen miles away. As the 7th Cavalry approached the Little Bighorn River, Reno, with three companies, was directed to cross the river and attack the village from the south. At that time Custer told Reno he would support him with the "whole outfit." As Reno approached the village numbers of warriors responded to meet him. Reno called a halt, had his men dismount and form into a skirmish line. After a short time Reno's skirmish line was flanked and he fell back to the woods along the river.
For a time Reno's battalion held out in the woods as more Sioux warriors responded to surround the soldiers. When Sioux warriors began to infiltrate the woods Reno decided his defensive position was untenable. At that time Arikara scout Bloody Knife was shot in the head while Reno tried to communicate with him. Reno mounted his troops and led them in a headlong charge that became a retreat and then a mad run for life to the bluffs across the river. Some men from Company G were left in the woods; those that left late were killed, those that stayed in the woods eventually made it back to Reno's defensive position across the river.
Soon the Sioux warriors left Reno's front to respond to Custer's threat further down river. Shortly before this Captain Benteen's battalion of three companies arrived at Reno's position in response to Custer's call to "Come Quick, Big Village…" Reno rushed out to Benteen and said, "For God's sake, Benteen, halt your command and help me! I've lost half my men!" In the meantime firing was heard down river and Captain Weir sought Reno's permission to move Company D towards the sound of the firing. Eventually the pack train came up and with the wounded Reno attempted to move the command to follow Weir.
The Sioux and Cheyenne warriors responded to the soldiers' appearance on the high ground to the south and forced Reno back to his original position on the bluffs. Into the next day, June 26, the seven companies of the 7th Cavalry (minus Reno's losses in the valley) commanded by Reno and Benteen held out under heavy fire from the Indian warriors. With the approach of General Terry's column, the warriors broke off the siege of Reno's position and the great village moved off to the south. Reno's men learned of Custer's fate from Terry's column on June 27.
Though the men under Reno's command were grateful for their survival, especially after learning the fate of Custer's battalion, in a short time following the battle Reno came under considerable criticism from disparate elements both within and outside the army. Reno was accused of not prosecuting the attack on the village as ordered and of not coming to Custer's support.
Though Reno's actions at the Little Bighorn were never officially criticized by the army command, he called for a Court of Inquiry into his actions at the battle to officially exonerate his name. On February 10, 1879, after extensive interrogation of the officers and civilians present at the battle, the court concluded the following:
…while subordinates in some instances did more for the safety of the command
by brilliant displays of courage than did Major Reno, there is nothing in his conduct which required (adverse criticism) from the Court.
Little Big Horn criticism was only one element which conspired to bring Reno down. The loss of his wife in 1874 was critical. Reno, formerly a moderate drinker, began drinking more resulting in altercations with fellow officers at post officers clubs. His loneliness for female company resulted in unwanted advances which initially resulted in a two year suspension from the army, 1877-79, and eventually to his dismissal from the army, effective April 1, 1880.
Major Reno spent the rest of his life in an effort to be reinstated in the army. He died as a result of cancer in the mouth, March 30, 1889.