He participated in the desert training in California and embarked with the division to Hawaii in July 1943 for defense of the islands. Adler participated in the coordination of the defense plans of Oahu and received Bronze Star Medal. The Sixth Division then conducted intensive jungle training until January 1944, when it received orders to reinforce allied units on Southwest Pacific. Adler participated in the New Guinea campaign until June 1944, when became ill and was shipped to the United States for treatment.