Shortly after his promotion to ensign on December 15, 1910, he was reassigned to the cruiser and attended the coronation ceremonies for King George V in London in 1911. In 1912, he returned to school to study latest naval artillery and submarine warfare techniques and was promoted to sub-lieutenant at the end of that year. In 1913, he served on the cruiser , followed by the battleship . He was promoted to lieutenant at the end of 1915, and transferred to the battleship . Although "Fusō" participated in operations in World War I against the Imperial German Navy, Inoue was not in any combat situations.