He continued to serve aboard the USS "Denver" and participated in operations off the Mexican Coast during the ongoing Occupation of Veracruz in Mexico. Long finally returned stateside in December 1914 and after one month Christmas leave, he was assigned to the newly created 4th Marine Regiment under Colonel Joseph H. Pendleton. His new unit subsequently sailed for expeditionary duty in Dominican Republic in June 1916, following the Coup d'état led by Dominican Republic's Secretary of War Desiderio Arias.