After graduation Hasbrouck taught school for a year and then went to Germany to continue his studies in preparation to joining the ministry. On his return to the United States he because a Minister of the Unitarian Society in Watertown, Massachusetts about 1849. In 1850 he would marry Martha W. Stickney whom would bear him 4 children between 1851 and 1859. Davis did not stay with the ministry long, abandoning that profession to study law. By 1854 he had been admitted to the Bar and opened an office in Boston. In 1855 Davis made a permanent move to Chicago, Illinois where he renewed the practice of law.
According to an excerpt in a book "In Memoriam" published after his death Davis was "tall, over 6 feet, well proportioned, far in complexion with light brown or perhaps auburn hair and blue eyes with a tinge of grey in them - he might be said to possess a more than common share of physical beauty. Naturally impulsive, he gave his soul to every act; and to this ardent nature he added a persistency of purpose rarely found in unison with it."
When the civil war broke out Hasbrouck Davis turned his law practice over to his partner and helped recruit the 12th Illinois Cavalry. He was commissioned Lt. Colonel of the 12th November 18, 1861 serving under German born Colonel Arno Voss.
The 12th Illinois Cavalry Regiment was organized at Camp Butler in February 1862. They would remain there until June 1862 training and guarding Confederate prisoners of war captured at Fort Donelson. After receiving their mounts on June 25, 1862 the 12th Illinois left Camp Butler for Martinsburg, Virginia.
Lt. Colonel Hasbrouck Davis and the 12th Illinois Cavalry saw action in and around Martinsburg, Bunker Hill, and Darkesville, Virginia in early September 1862. They were briefly in Williamsport, Maryland on September 11 before returning to Martinsburg. On the 12th they vacated Martinsburg with Brigadier General Julius White's command and headed southward to Harpers Ferry to join Colonel Dixon Miles Union garrison there. They were engaged in the defenses of Harpers Ferry on September 13 and 14th, 1862.
By September 13, 1862 the Union garrison at Harpers Ferry was surrounded by Confederate forces under the command of Stonewall Jackson. Confederate artillery shelled the town on the 14th and things look bleak for the Union forces. It was inevitable the garrison would have to surrender.
The leaders of the Union Cavalry at Harpers Ferry, predominately Colonel Benjamin Franklin "Grimes" Davis of the 8th New York Cavalry and Lt. Colonel Hasbrouck Davis of the 12th Illinois consulted with Julius White about the possibility of escaping the doomed town. They went to Colonel Dixon Miles who reluctantly gave his consent for the breakout. Miles in Special Order #120 put Colonel Arno Voss of the 12th Illinois in overall command of the expedition because he was the ranking officer.
About 8:00 pm on September 14, 1862 about 1500 Union cavalry, led by Grimes and Hasbrouck Davis and a local guide left Harpers Ferry via the pontoon bridge that spanned the Potomac to the base of Maryland Heights in Maryland. The men would follow the line of the Potomac to near Williamsport, MD., where they would go cross country, finally winding up in Greencastle Pennsylvania along with part of Confederate General James Longstreet's supply train. The escape ranks as one of the most daring events in civil war history.
Hasbrouck Davis would be promoted Colonel of the 12th Illinois Cavalry on August 11, 1863 and Brevet Brigadier General March 13, 1865. He would lead the regiment throughout the remainder of the civil war resigning his commission in August 1865. After leaving the army Davis resumed his law practice in Chicago.
Find A Grave photo by Merry Hill
On October 19, 1870 Hasbrouck Davis would be lost at sea of the coast of Ireland aboard the steamer Cambria. His body was never recovered.