On 13 September 1943, during the Battle of Lae, the platoon to which Private Kelliher was attached came under very heavy fire from a concealed Japanese machine gun, at Heath's Plantation. The machine gun inflicted severe casualties and prevented the platoon's advance. Private Kelliher suddenly, on his own initiative, dashed towards the post and hurled two grenades at it, which killed some of the enemy. He returned to his section, seized a Bren gun, dashed back to the enemy post and silenced it. He then asked permission to go out again to rescue his wounded section leader, which he accomplished successfully under heavy fire from another enemy position.