During a Japanese counterattack on that day, on the Villa Verde Trail in Luzon, the Philippines, he voluntarily stayed behind and provided covering fire while the rest of his unit retreated.

Private First Class Shockley's official Medal of Honor citation reads: He was in position with his unit on a hill when the enemy, after a concentration of artillery fire, launched a counterattack.

He maintained his position under intense enemy fire and urged his comrades to withdraw, saying that he would "remain to the end" to provide cover.

Knowing that the only route of escape was being cut off by the enemy, he ordered the remainder of his squad to withdraw to safety and deliberately remained at his post.

Shockley, facing certain death, sacrificed himself to save his fellow soldiers, but the heroism and gallantry displayed by him enabled his squad to reorganize and continue its attack.