At the beginning of the Civil War, Federal troops secured Alexandria as Union territory. Former slaves, called contrabands, poured in to obtain protection from their former masters. Due to overcrowding, mortality rates were high. Authorities seized an undeveloped parcel of land on South Washington Street, and by March 1864, it had been opened as a cemetery for African Americans. Between 1864 and 1868, more than 1,700 contrabands and freedmen were buried there. For nearly eighty years, the cemetery lay undisturbed and was eventually forgotten.