[2] He served in the regiment commanded by his elder brother, Colonel Don Morrison, in the Mexican–American War, and fought in the Battle of Buena Vista.

[2] After the war, Morrison returned to St. Louis, Missouri, and read law in the office of his brother, who was a successful attorney.

[8][9][10] In August 1886, former Chief Justice David S. Terry petitioned the Legislature to remove the increasingly ill Morrison from the court.

[11] In February 1887, Morrison suffered a stroke and died a week later at his rooms at the Occidental Hotel on March 2, 1887.

[12] On April 19, 1887, Governor Washington Bartlett appointed Niles Searls as the next chief justice.