 During his assignment Davidson taught basic military tactics and techniques to classes of 50 to 200 officer candidates.In July 1943, Davidson was detached as a captain from Marine Corps Schools and assigned to the 4th Marine Division, commanded by Major General (later General) Harry Schmidt, being formed at Camp Pendleton, California.Davidson performed several staff and command roles in 2nd Battalion, 23rd Marines, and served with this unit throughout combat operations against Roi-Namur in the Battle of Kwajalein in the Marshall Islands (January 31 – February 3, 1944).