Haupt also experimented with bridge demolition using torpedoes (inserted in holes drilled in trusses) and also discussed in a November 1862 report various methods of destroying locomotives (firing a cannon ball through the boiler was irreparable; locomotives with fireboxes drained then fired could be repaired). He also tested a lightweight 2-clamp "rail-twister" for use in raids behind enemy lines. Offered promotion again in early autumn 1863, Haupt hinged his acceptance on three conditions: that a central Bureau of U.S. Military Railroads be established to inspect, direct, and receive reports concerning construction and operation of all military railroads; difficulties with commanding generals be avoided through consultation and cooperation within their departments; the chief of the bureau should be free to move wherever his personal presence was necessary or to attend to whatever public or private business required his attention. The War Department declined to accept such terms. Haupt's appointment was eventually rescinded on September 5, 1863, and he left the service on September 14. During that year as a general, however, he made an enormous impact on the Union war effort. The Civil War was one of the first wars in which large-scale railroad transportation was used to move and supply armies rapidly over long distances. Haupt assisted the Union Army of Virginia and Army of the Potomac in the Northern Virginia Campaign, the Maryland Campaign, and was particularly effective in supporting the Gettysburg Campaign, conducted in an area he knew well from his youth. His hastily organized trains kept the Union Army well supplied, and he organized the returning trains to carry thousands of Union wounded to hospitals. After the Battle of Gettysburg, Haupt boarded one of his trains and arrived at the White House on July 6, 1863, becoming the first to inform President Lincoln that General Robert E. Lee's defeated Confederate army was not being pursued vigorously by Union Major General George G. Meade. During his service, Haupt developed and implemented "general principles of railroad supply operation" and "also detailed methods of construction and destruction of railroad equipment". His two main principles were that the military should never interfere with the efficient running of the railroad and that rolling stock should be emptied and returned promptly to enable their re-use as transport. After his war service, Haupt returned to railroad, bridge, pipeline, and tunnel construction. He worked with the Richmond and Danville Railroad then was the general manager of Piedmont Air-Line Railway (from Richmond, Virginia, to Atlanta, Georgia), 1872 to 1876; Tide Water Pipe Line Company, 1875- ; general manager of the transcontinental Northern Pacific Railroad, 1881 to 1885; president of the Dakota and Great Southern Railroad, 1885 to 1886.