Born in Paris, Kentucky, Colonel Dickey moved to Macomb, Illinois in 1834 to study law under Cyrus Walker and was admitted to the Illinois Bar in 1835. The next year, he moved Rushville, Illinois where he edited a newspaper and speculated in real estate in addition to his legal practice. In 1839, he again moved, this time to Ottawa, Illinois where he continued his legal career.
Upon the outbreak of the Mexican-American War he raised a company of volunteers and received a commission as captain.
At the end of the war, he returned to Ottawa, Illinois and was elected a judge of the Illinois Ninth Judicial Circuit in 1848. He resigned his position as judge in 1851 but continued in the practice of law.
He was a prominent political supporter of Stephen A. Douglas, making many stump speeches for him in 1858 and 1860. Dickey was authorized by the State of Illinois to raise a company of cavalry in August 1861.
This company became the nucleus of the 4th Regiment Illinois Volunteer Cavalry, the recruitment of which resulted in a dispute between Colonel Dickey and Illinois Governor Richard Yates over the commissions to be granted to the officers of the regiment, a valuable tool of political patronage.
In the end, Governor Yates accepted Colonel Dickey"s choices and granted them their commissions. The 4th Illinois Cavalry completed its organization and was officially mustered into service on September 26, 1861. The regiment was sent to Cairo, Illinois soon after it was mustered in.
Colonel Dickey commanded the regiment during the advance of Grant"s army on Fort Henry, serving as the scouts and screening force, served in a supporting role during the attack on that place, and then again led the advance on Fort Donelson.
Colonel Dickey"s regiment was shipped to Pittsburg Landing, Tennessee where it participated in the Battle of Shiloh. From 1868 to 1870, he served as an Assistant Attorney General for the United States for all suits in the court of claims, and often argued before the United States Supreme Court in that role.
Dickey was elected a justice of the Illinois Supreme Court in December 1875 and held that office until his death in 1885.