His father was George Morell, the chief justice of the Michigan Supreme Court.

He graduated from the United States Military Academy, first in his class of 56 cadets, in 1835 and was commissioned a brevet second lieutenant in the Corps of Engineers.

He was promoted to brigadier general of volunteers on August 9, 1861, and served in brigade and division command in the Army of the Potomac during the Peninsula Campaign.

Morell testified on Porter's behalf at the court-martial, effectively ruining his military career.

He commanded the Draft Depot in Indianapolis, Indiana, for most of 1864 and was mustered out from volunteer service on December 15, 1864.