Fuel was a problem. Southern locomotives were fueled by wood--a great deal of it. As the Confederate government pulled skilled railroad employees out of their civilian jobs and into the military, the railroad companies became badly understaffed. Replenishing the wood-yards at the depots soon became impossible. Train crews eventually took to stopping along their route to chop and load wood as it was needed.
Accidents also wrecked a lot of equipment. Because telegraph communication was sporadic at best, railroad crews were often unaware of broken rails and collapsed bridges. Cattle on the tracks caused accidents, sparks from the locomotives' wood fires burned cars, and boilers exploded.
During the war, railroads were second only to waterways in providing logistical support for the armies. They were also vital to the economies of the divided nation. A great deal has been written about railroads in the war, and in particular the spectacular engineering feats of the U.S. Military Railroads’ Construction Corps under Herman Haupt.
Large military forces were, of course, the worst danger to railroads. They supplied the units that were on campaign, railroads were often major objectives–an army without supplies cannot operate for long. Since the only sure way to deal with large-scale threats was with a force of similar size, armies often stayed near the railroad tracks.
In special situations, locomotives served as rams. Troops might start a locomotive down a track with a full head of steam to damage an enemy train or railroad facilities, or to attack troops. On one occasion, Confederate soldiers lurking near a burned bridge suddenly saw a burning ammunition train hurtling straight toward them, forcing them to skedaddle. Troops sometimes launched individual cars, also set ablaze, against opponents, or used them to burn bridges. The potential for such rail-borne threats prompted commanders to build obstructions on the tracks.
While trains might serve as artillery bait, they could also transport heavy guns to the battlefield. Commanders took this idea a step further during the war by mounting heavy artillery pieces, which were very difficult to maneuver in the field, on flatcars for combat operations. Locomotives or manpower propelled these railroad batteries, dispensing with the horses that normally were the prime movers for the guns and eliminating the need to hitch or unhitch the gun from the horse team. This enabled a battery to fire on the move, a significant advantage over its horse-drawn counterparts.