An excellent question MC. I never thought of "train" being literally a steam engine and rail cars......just that huge "tail of trains, horse and wagons, light rail and ultimately humans slogging through the mud carrying sacks of bread loaves, water, stew etc into the trenches. Ultimately the soldiers on both sides became the pack animals as mules or horses could not reach the front lines because of the mud. Train.....that force which brings up every conceivable resource needed by a modern army to fight it's war. The so called train, has always been needed in the History of human warfare. Even though I am totally unschooled in today's warfare, I would venture to say that the more complicated the machines of war evolve, then the even more important "the train" becomes. This is a double edged sword if you look at WW2,......German tanks, far superiour to the Sherman, but the Sherman easily fixed, manufactured and replaced. The big problem....the human element, not easily replaced because it had to be highly trained to operate the machine. However, certainly not as trained as they must be today. Tony can speak to this much better than I as a poor civilian. He is a modern day tanker with years of experience.