War Department Light Railways The War Department Light Railways were a system of narrow gauge trench railways run by the British War Department in World War I . Light railways made an important contribution to the Allied war effort in the First World War , and were used for the supply of ammunition and stores , the transport of troops and the evacuation of the wounded . Track gauges . Different track gauge s were used in different parts of the world including , , and . The military light railways in France were of gauge and used a variety of steam and petrol locomotives from French , British and American builders . The Germans installed their gauge Feldbahn system early in the war . Trench railways of the World War I western front produced the greatest concentration of minimum gauge railway locomotives observed to date . Development . Britain came to the belated realisation that it needed a flexible and reliable method of supplying the front lines , bringing shells , timber , and fodder from the rear areas and their standard gauge supply points . narrow gauge light railway s were the solution . Hundreds of locomotives were built by companies such as Hunslet , Kerr Stuart , ALCO , Davenport , Motor Rail and Baldwin to work these lines . Also , Model T Ford conversions were used . Thirty or so Companies were formed within the Royal Engineers to staff the lines . These were mostly British ex - railwaymen pressed into service , though Australian , South African and Canadian gangs served with distinction . An American unit also served under the British flag . Each area of the front would have its own light rail to bring up materiel . The British perfected roll on roll off train ferries to bring fodder and supplies direct from England via train ferries to France . Northern French rail lines were under direct military control of the Army in the area . By 1917 , the Canadians led the way in showing the utility of light railways . Having built thousands of miles of new frontier track in Western Canada in the previous decades , these " colonials " , led by J . Stewart , supplied the Canadian Corps who went on to victory at Vimy . From this the light railways were expanded to of track , which supplied 7 , 000 tons of supplies daily . The ebb and flow of war meant that rail lines were built and rebuilt , moved and used elsewhere , but by the latter years of Passchendaele , Amiens and Argonne , light railways came into their own and pulled for the final victory . WDLR locomotives . A large number of locomotives ( mostly of gauge ) was ordered for the WDLR . These included : http : / / www . wdlr . org . uk / wdlr / images / preservedaus / 1218 _ 1 . jpg Steam . Hunslet 4 - 6 - 0 Locomotive 1218 of 1916 , formerly of Gin Gin Mill . Currently with D . Revell , Weewaa , Queensland . Photo by I . Hughes at : http : / / www . wdlr . org . uk / wdlr / images / preservedaus / 1218 _ 1 . jpg link title Internal combustion . A few captured German feldbahn locomotives were also used but these usually had short lives because no spare parts were available for them . Other locomotives . Both the French Army and the U . S . Army had their own locomotives , which included : After the war . Probably the most famous of these war service engines were of class 10 - 12 - D , built by the Baldwin Locomotive Works , U . S . A . Nearly 500 were built and those that survived the war found new homes around the world . Many went to India and after the war a few went to railways in Britain including :