Describes the narrow gauge railways of Belgian West Flanders and French Flanders before WW1.

The Somme sector of the Western Front was held by French forces until early 1916, when the British and Dominions Third and Fourth Armies moved into the northern part, before the joint First Battle of the Somme from July to November 1916. In 1917, with the German withdrawal to the Hindenburg Line, British responsibility moved further south.