With the outbreak of the American Civil War, he would join the United States Volunteers on the Union side and quickly receive an appointment to brigadier general.

He would become one of the war's oldest surviving officers, and in 1866, he was awarded an honorary brevet rank of brigadier general in the parallel US Regular Army.

Prince would continue to serve as a paymaster until retiring, and eventually move to England where he lived in financial comfort.

However, despondent over constant physical pain from war wounds that had never entirely healed, he committed suicide in a London hotel at the age of 81.

[1][additional citation(s) needed] Prince enrolled as a cadet at the United States Military Academy on September 1, 1831 and graduated 30th in his class on July 1, 1835.

He participated in several battles, including at Oloklikaha, Thlonotosassa Creek, and Camp Izard where he was wounded in action while defending the fort.

By the end of 1838, however, the army had transferred Prince and his company to assist with resettling the Muscogee Creek as part of the US government's Indian removal policy.

[5] After the Florida war ended in 1842, Prince would spend the next several years in various posts and roles, including recruitment, Coast Survey, and finally in late 1846, adjutant of the 4th infantry.

[7] John Baillie McIntosh later recalled Prince's actions: The cool deportment of the experienced officers at this time, particularly of my acting adjutant.

He advanced with the battery, and succeeded in breaching the barricades, and preparing the way for our troops to charge, which was made under a heavy fire from the enemy.

[4] On September 8, 1847, at the Battle of Molino del Rey, Prince was severely wounded with an injury that would trouble him for the remainder of his life.

[15][page needed] At the outbreak of the Civil War, Prince was working in the Army's pay department as a paymaster.

[20] He described the moment of his capture in a report to the military command:On approaching the right I perceived that the firing in the other brigades had ceased, which forcibly impressed upon me the necessity of learning immediately something of the day.

While walking my horse in the dense corn, where the ground was heavy, my bridle was seized, and I perceived that I was in the midst of enemies before otherwise discovering any person to be there.

[27] His participation in the Mine Run campaign came under scrutiny as William H. French blamed his failure to exploit a Confederate advantage on one of his "division commanders", widely considered to be Prince.

While in the process of moving his belongings from Maine to Massachusetts, the facility where they were stored caught fire, causing him to lose a significant amount of his private papers, books, records and valuables.

Such being the case with the life of the writer, his apology to the world is by these terms made through his most beloved and most intimate friends, who, he trusts, will appreciate the relief to him and ceaseless distress, which in his opinion, ought to be brought by the physician who is summoned with his drugs surely for that purpose when not to cure.