He was subsequently attached to the battleship USS "Maine" and served as senior Watch officer under Captain William B. Caperton until August 1909, when he was ordered back to the United States Naval Academy for his second tour as an instructor in the Department of Physics and Chemistry. Greenslade was transferred to the battleship USS "Michigan" in June 1911 and served consecutively as ordnance officer and navigator for next three years. During the Veracruz Expedition, he led "Michigan landing battalion" ashore. He was promoted to Lieutenant commander on March 4, 1911.