The need to keep the trains running to the front resulted in some amazing displays of engineering prowess during the Civil War. This bridge in Virginia was constructed of "round sticks cut from the woods, and not even divested of bark" in May 1862.
The Army boasted that the bridge was built in nine working days, using the labor of the "common soldiers of the Army of the Rappahannock, under the supervision of Brigadier General Herman Haupt, Chief of Railroad Construction and Transportation."
The bridge may look precarious, but it carried up to 20 trains a day.