Trail below Glorieta Pass. Slough and Scurry fought an initially indecisive action at the Battle of Glorieta Pass. The Texans were pushing the Coloradans back, but the battle was turned to a victory for the Union after Slough sent Major John M. Chivington on a flank attack, which destroyed the Confederate's supply train. The battle was considered a Union strategic victory but a Confederate tactical victory. Slough's regiment had stopped the advance of the Confederates, which soon abandoned New Mexico and retreated back to Texas. Following the battle, Slough received direct orders from Canby to remain at Fort Union. Though dated and sent before the battle, while the Confederate army divided Canby and Slough's communication line, the order has been debated as confirmation or not that Slough had disobeyed Canby's orders by leaving Fort Union in the first place. Slough met with Canby, determined the war in New Mexico was over, resigned his commission, and immediately headed to the Eastern theater. At the first anniversary after the battle of Glorieta, his former Colorado troops sent him a gold inlaid sword as thanks for making the rag tag volunteers into a fighting force. In response Slough wrote: “Remember the holy character of the cause in which you are engaged. Remember that you are American soldiers, battling in the cause of universal freedom.” Through his wife's McLean family ties (the chief justice of the U. S. Supreme Court was a relative), Slough went to Washington, D.C., where he was given command of a brigade in the Shenandoah Valley during Stonewall Jackson's Valley Campaign of 1862. His forces were stationed at Harpers Ferry and saw little action. He was appointed brigadier general of volunteers of August 25, 1862, and became the military governor of Alexandria, Virginia. For the rest of the war, he commanded the District of Alexandria. In December 1862, he sat on the court-martial that convicted Maj. Gen. Fitz John Porter of disobedience and misconduct. Postbellum career When the Civil War ended in 1865, Slough resigned his commission and opened a law office in Washington, D. C. In January 1866, United States President Andrew Johnson, appointed him to serve as chief justice of the New Mexico Territorial Court. One of his first and most personal acts was to seek funds to mark the graves of the Union dead and place monuments at the Civil War battle sites of Valverde, Apache Canyon,