World War I on the Entente side and declared war on the Austro-Hungarian Monarchy. Electrification of the London underground lines, a moral victory On the District and Metropolitan Railways, the use of steam locomotives led to smoke-filled stations and carriages that were unpopular with passengers and by the early Twentieth Century electrification was seen as the way forward. A tender was announced for an electric system, and the largest European and American companies applied to win the tender. However, when the experts of the railways compared the designs from the Ganz Works to the offers of the other large European and American competitors they concluded that Ganz Works' technology was cheaper and more reliable and described its technology as a "revolution in electric railway traction". In 1901 a Metropolitan and District joint committee recommended the Ganz three-phase AC system with overhead wires. Initially this was unanimously accepted by both parties, until the District found an investor, the American Charles Yerkes, to finance the upgrade. Yerkes raised £1 million (1901 pounds adjusted by inflation are £) and soon had control of the District Railway. His experiences in the United States led him to favour of the classic DC system, similar to that in use on the City & South London Railway and Central London Railway. The Metropolitan Railway protested about the change of plan, but after arbitration by the Board of Trade the DC system was adopted. Vienna, invention of the phase converter During World War I between 1916 and 1917, Kandó was a lieutenant completing military service for the Ministry of Defence in Vienna. He worked out a revolutionary system of phase-changing electrical hauling, whereby locomotives were powered by the standard, 50-period, single-phase alternating current used in the national energy supply system. He was the first who recognised that an electric train system can only be successful if it can use the electricity from public networks. In 1918, Kandó invented and developed the rotary phase converter, enabling electric locomotives to use three-phase motors whilst supplied via a single overhead wire, carrying the simple industrial frequency (50 Hz) single phase AC of the high voltage national networks. Hungary To avoid the problems associated with the use of two overhead wires, Kandó developed a modified system for use in Hungary. Power semiconductors not having been invented yet in the 1930s, the Kandó V40 locomotives' systems relied on electromechanics and electrochemistry. Kandó synchronous