rolling mills, machine shops, factories, roundhouses and repair yards that produced and maintained rails, bridging equipage, locomotives, rolling stock, signaling gear, and telegraph equipment. In peacetime the South imported all its railroad gear from the North; the Union blockade completely cut off such imports. The lines in the South were mostly designed for short hauls, as from cotton areas to river or ocean ports; they were not designed for trips of more than 100 miles or so, and such trips involved numerous changes of trains and layovers. The South's of track comprised enough of a railroad system to handle essential military traffic along some internal lines, assuming it could be defended and maintained. As the system deteriorated because of worn out equipment, accidents and sabotage, the South was unable to construct or even repair new locomotives, cars, signals or track. Little new equipment ever arrived, although rails in remote areas such as Florida were removed and put to more efficient use in the war zones. Realizing their enemy's dilemma, Union cavalry raids routinely destroyed locomotives, cars, rails, roundhouses, trestles, bridges, and telegraph wires. By the end of the war, the southern railroad system was totally ruined. Meanwhile, the Union army rebuilt rail lines to supply its forces. A Union railroad through hostile territory, as from Nashville to Atlanta in 1864, was an essential but fragile lifeline—it took a whole army to guard it, because each foot of track had to be secure. Large numbers of Union soldiers throughout the war were assigned to guard duty and, while always ready for action, seldom saw any fighting. Southern Unionists Southerners who were against the Confederate cause during the Civil War were known as Southern Unionists. They were also known as Union Loyalists or Lincoln's Loyalists. Within the eleven Confederate states, states such as Tennessee (especially East Tennessee), Virginia (which included West Virginia at the time), and North Carolina were home to the largest populations of Unionists. Many areas of Southern Appalachia harbored pro-Union sentiment as well. As many as 100,000 men living in states under Confederate control would serve in the Union Army or pro-Union guerilla groups. Although Southern Unionists came from all classes, most differed socially, culturally, and economically from the region's dominant pre-war planter class. Sherman's March By 1864, the top Union generals Ulysses S. Grant and William T. Sherman realized the weakest point of the Confederate armies was the