Following the Texas Revolution, Mijares retired from the navy and married Dolores Aviles in June 1847.
As a Lieutenant, he was sent to Baja California Sur, joining the command of Captain Manuel Pineda Munoz, who had defeated a U. S. Navy attempt to capture Mulege in the Battle of Mulege and was moving south to attack American forces in La Paz.
[1] Pineda sent Lt. Mijares and bajacalifornio guerrilla leader Jose Matias Moreno with about 100 men to San José del Cabo, where the U. S. Navy Commodore William Shubrick had left a garrison of four passed midshipmen and twenty marines, and twenty friendly bajacalifornios from the town, along with a 9-pound carronade under Lieutenant Charles Heywood.
Upon reaching San José del Cabo on November 19, 1847 the force offered terms of surrender to Lt. Heywood, which were refused.
[1] Mijares moved forward with a forlorn hope to seize the piece of artillery and distract the defenders from the main assault on the walls.