13 Bainbridges were officially designated as the Navy's first TBDs when authorized by an Act of Congress on 4 May 1898 under the fiscal year 1899 program (with the remaining three being ). Due to construction difficulties the Bainbridges were completed 1901–02, thus too late for the Spanish–American War. However, the destroyer type was instituted in the US Navy, as it had been in the Royal Navy around 1895 with the A-class destroyers. No further torpedo boats were constructed for the US Navy until the outbreak of World War II in Europe, and by then they had no design relationship to destroyers (see PT boats). The Imperial German Navy of 1898–1918 used the term "torpedo boat" for anything up to a large destroyer in size. Armament At 420 long tons normal displacement, the Bainbridges were twice as big as most previous torpedo boats. The extra displacement was used for a greatly increased gun armament and a sufficient engineering plant to rival the torpedo boats in speed ( vs. ). The torpedo armament remained at two torpedo tubes; although the torpedo boat's mission was being transferred to the destroyer, apparently increased gun armament was more important to the designers than increased torpedo armament. The gun armament of two /50 caliber guns and five 6-pounder () guns was a great increase over the four 6-pounder guns of the torpedo boat Farragut. It reflected a desire to quickly disable torpedo boats before they could get within range of friendly battleships. Future destroyer classes included progressive increases in armament. The class was equipped with one or two depth charge racks during World War I for the anti-submarine mission. Engineering The best available technologies of coal-fired boilers and triple-expansion engines were used for propulsion, although steam turbines would be adopted in the next generation of US destroyers, beginning with the launched in 1908. The need for faster destroyers was to be a significant driver of naval propulsion technology throughout the type's future development. Bainbridge had four Thornycroft boilers supplying steam to two triple-expansion engines totaling (design). She made on trials at . Normal coal capacity was . Hopkins also had four Thornycroft boilers supplying steam to two triple-expansion engines totaling 7,000 ihp (design). She made on trials at . Normal coal capacity was lower though, at . Lawrence had four Normand boilers supplying steam to two triple-expansion engines totaling (design). She made on trials 8,400