Commissaryman First Class Mocklin served aboard the mine sweeper USS Pirate (AMS-275) in Korean waters. His ship was sweeping enemy mines three miles off Sin-Do Island when it struck an enemy mine and sank on 12 October 1950. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Mocklin was awarded the Purple Heart, the Combat Action Ribbon, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.