The 22nd Marines were sent to the Pacific theater and subsequently arrived to Samoa at the end of June. Colonel Walker subsequently commanded the regiment, which was designated as independent unit during the island defense and also conducted the intensive jungle training. Walker did not see combat until February 1944, when his unit participated in the Battle of Eniwetok. He landed on Engebi Island on 18 February following the Naval bombardment. Walker placed his command post on the beach and participated in the hand-to-hand fighting, when almost one thousand of Japanese soldiers were killed with only 85 dead and missing plus 166 wounded US soldiers. On 22 February, Walker and his 22nd Marines invaded the Parry Island and continued to fight the enemy for next 10 hours.