Born into a military family in Utah and raised in Berkeley, California, Mearns started at West Point in July 1934 graduating with a B.S.

[1][2] Following the United States entry into World War II, Mearns graduated from the Command and General Staff School in 1942[2] and transferred to III Corps where he served as assistant Operations officer (G-3).

[4] Mearns was awarded the Silver Star for his actions on 16/17 January 1944 when his unit was trying to cross the Rapido River during the Battle of Monte Cassino.

[4] On 6 August 1967 Major General Mearns assumed command of the 25th Infantry Division at Củ Chi Base Camp.

[8][9] This article incorporates public domain material from websites or documents of the United States Army Center of Military History.