Cates led the 1st Marines at Guadalcanal, for which he was awarded the Legion of Merit with Combat "V". He then assumed command of the 4th Marine Division in the Marianas operation, the Tinian campaign and the seizure of Iwo Jima. For his services at Tinian, Cates received the Navy Distinguished Service Medal and a Gold Star in lieu of a second award for his service at Iwo Jima. The planning for Tinian included the first complete aerial reconnaissance of an enemy base by the key commanders, including Cates. Near the end of the fighting at Iwo Jima, Cates attempted to persuade the remaining Japanese brigade to surrender honorably rather than fight to the death.