Sentence:  An offensive against Germany would require large forces and offered no certain prospect of success. An attack on Austria promised great victories, the destruction of the whole Austrian army and of the Austro-Hungarian state itself, the reordering of half of Europe—and meanwhile Russia would need only small forces to defend herself against the Germans, inflicting on them the disadvantages of poor roads and Russian <WSD>broad-gauge</WSD> lines. 
Meaning of the word marked with <WSD> tags:  Having a wide gauge.