During this time the passage of the Fortification act of 1888 brought before the department the subject of rehabilitating the coast defenses, the purchase of gun forgings and experimenting with gun steel, breech-loading mortars, steel breech-loading rifles and disappearing gun carriages, and Lieutenant Crozier was sent to Europe to make a study of these subjects and to purchase the best models for the purpose of manufacturing in the United States with the advantage of the knowledge and experience which had been gained in Europe, where more progress had been made in these directions. On his return in 1889 he was given charge under the chief of ordnance of the gun-carriage work of the department. He designed many of the carriages used in the siege and sea-coast service, patented on February 25, 1896, his disappearing gun carriage (of which he was joint inventor with Colonel A. R. Buffington) which came into universal use in the United States. Lieutenant Crozier also invented a wire-wrapped rifle, April 9, 1901, a 10-inch gun of which type was built and tested by the government. After trial two boards of officers reported unqualifiedly in its favor. It is the only wire-gun ever recommended for adoption by expert boards in the United States.
Lieutenant Crozier was promoted to the rank of captain United States army, 1890; and in 1892, he was detailed as a member of the ordnance board with station in New York city and work in connection with the proving ground at Sandy Hook, New York harbor. In 1896 he was again assigned to duty in the office of the chief of ordnance at Washington, District of Columbia. He was made inspector-general with the rank of major. United States volunteers, and served from May 17 to November 30, 1898, in inspecting the sea-coast fortifications of the Atlantic and gulf coasts with instructions from the secretary of war to take all measures in his judgment necessary to insure the efficiency of the armament and the instruction of the garrisons. This order was in anticipation of an attack from the Spanish fleet, reported to have the undefended sea coast of the United States as the object of attack. In 1899 he was appointed by the president a member of the United States Commission to the International Peace Conference at The Hague, and he served as a member of that body during its continuance. He served on the staffs of Generals Bates and Schwann in the provinces of Cavite, Batangas, Laguna and Tayabas, Philippine Islands, in the campaign of January, 1900, and in July, 1900, he was assigned as chief ordnance
