Repair work by the military railroad corps.It was not only the daring Confederates with which the United States military construction corps had to contend, but the elements as well. In April, 1864, a freshet swept away this much abused structure. The standard size parts, ready prepared, were stackedintherailroad yards awaiting calls from the front. Cars were held always ready, and the parts ordered by wire were hurried away to the broken bridge as soon as a competent engineer had inspected the break and decided what was needed. The remainder of the work of the corps after this material reached the spot was a matter of minutes, or at the most of a few hours. The lower photograph shows the Bull Run bridge being repaired.