In November 1863, Federal troops occupied Kingston Springs as headquarters for the supervisors of the U.S. Military Railroad Construction Corps, who oversaw construction of this section of the Nashville and Northwestern Railroad. When completed, the line connected Nashville to the major Union depot at Johnsonville on the Tennessee River. Federal commanders impressed both free blacks and escaped slaves to build the railroad alongside Irish immigrants, and together they constructed three wooden trestles near here as well as bunkers, blockhouses, and fortifications to guard the line. The black laborers were inducted into the 12th and 13th United States Colored Troops in 1863 and stationed in Kingston Springs. Col. William W. Wright, chief of engineers, reported that about 500 men of the 13th USCT began the work on November 19, 1863, and that the 12th USCT relieved them on May 10, 1864. Gen. Alvan C. Gillem commanded both units. After construction was completed, the 13th USCT remained on guard duty along the railroad until November 30, 1864.