McCampbell formed Fighter Squadron 15 (VF-15) on September 1, 1943 and led the squadron before being reassigned as Commander of Air Group 15 (AG-15) in February 1944 to September 1944.
On June 19, 1944, during the "Marianas Turkey Shoot," Commander McCampbell shot down five Japanese Yokosuka D4Y 'Judy' dive-bombers, to become an "ace in a day".