 In 1943, he served as Commander of Marine Forces overseeing Guadalcanal, Tulagi, and the Russell and Florida Islands.He was decorated with the Legion of Merit for his merits during Guadalcanal campaign.On April 1, 1944, del Valle, as commanding general of the Third Corps Artillery, III Marine Amphibious Corps, took part in the Battle of Guam and was awarded a gold star in lieu of a second Legion of Merit.