Citation... For conspicuous leadership above and beyond the call of duty involving personal valor and intrepidity at an extreme hazard to life. As commander of the 5th Bomber Command during the period from 5 September 1942, to 5 January 1943, Brig. Gen. Walker repeatedly accompanied his units on bombing missions deep into enemy-held territory. From the lessons personally gained under combat conditions, he developed a highly efficient technique for bombing when opposed by enemy fighter airplanes and by antiaircraft fire.

On 5 January 1943, in the face of extremely heavy antiaircraft fire and determined opposition by enemy fighters, he led an effective daylight bombing attack against shipping in the harbor at Rabaul, New Britain, which resulted in direct hits on 9 enemy vessels. During this action his airplane was disabled and forced down by the attack of an overwhelming number of enemy fighters.