The Manchester and Augusta was built in 1894, by the Walters Atlantic Coast Line group. Starting from Sumter, it originally proceeded through Orangeburg to Denmark, where it met and connected with the SC & Georgia Railroad's mainline between Branchville and Augusta.
The Walters ACL group was reluctant to depend on the SC & Ga Railroad, which was already associated with rival Southern Railways, for access to Augusta from Denmark. For this reason, by 1899 the M&A was extended beyond the SC & Ga from Denmark through Barnwell to Robbins, SC , where it connected to the ACL-affiliated Charleston & Western Carolina, giving entry to Augusta independently of the SC & Ga and creating a route between Florence and Augusta that bypassed congested Columbia. The extended line ran just south of downtown Barnwell through a deep cut, crossing underneath the north-south former Carolina Midlands line that is now an abandoned Southern line.
This rail line was severed by CSX in the 1980's and abandoned from Cope, where a coal-fired electric generating plant is located on the bank of the South Fork Edisto, to Robbins which now lies on the grounds of the Savannah River Site. This abandonment allowed CSX to dispense with large bridges over two rivers as well as redundant trackage. The remaining section from Sumter to Cope still serves numerous industries located on that line from Sumter through Orangeburg, and on the CSX Creston branch, as well as the power plant. Remnants of the western end to the site of Dunbarton serves the Savannah River site railroad network, the federal reservation where nuclear weapons materials were formerly made.
The roadbed through Denmark was very fresh in 2001. ROW, old platforms and apparent warehouses, and a plate girder bridge by which the abandoned Southern line crossed over the cut, were visible off SC 3 in Barnwell as of the early 2000's.
I believe that the spur at Denmark is not technically abandoned, A few years ago there was an ethanol customer and I have seen cars stored on the spur known to us at CSX as the Denmark Connection