On February 23, 1952, the 25th Division, under the command of Major General Ira P. Swift, was in the front line in the center of the X Corps sector near Mundung-ni northeast of the Hwach'on Reservoir.

The division assumed the front line routine of patrols, ambushes, artillery exchanges, and bunker maintenance.

During a lull in the shelling, the men of the 27th inside the castle were able to spot crawling KPA soldiers, whose intentions were to cut off the forward bunkers and Outpost Agnes.

Martinez, along with Private First Class Paul G. Myatt,[3] remained at his post and with his machine gun inflicted numerous casualties on the attacking troops.

When he ran out of ammunition, he retreated to a bunker destroyed by enemy shelling and from there continued his assault with a Browning automatic rifle.