After Dolley Madison sold Montpelier in 1844, the estate became the site of major events in the 1860s. Throughout the winter of 1863 and 1864, as many as 4,500 Confederate troops camped there as part of a defensive line south of the Rapidan River, and on May 4, 1864, they marched directly into the Battle of the Wilderness, opening the 1864 Lee-Grant campaign. Following defeat at Gettysburg, Robert E. Lee had retreated to Orange County and positioned his army along a 30-mile front behind the Rapidan River, with observation posts on high ground such as Clarke Mountain, and after the Union army's unsuccessful efforts to move south, ending with the Mine Run campaign in November 1863, both sides settled into winter quarters until spring. One of the three brigades camped at Montpelier was General Samuel McGowan's South Carolina brigade, whose soldiers patrolled the Rapidan River and improved the road to Orange by cutting trees into heavy boards and laying them over the rutted surface so troops could deploy quickly; when Union forces were detected early on May 4, 1864, at Germanna Ford, about 30 miles east of Montpelier, McGowan's 1,500-man brigade marched out and within 24 hours was fighting in the Battle of the Wilderness, where one third of his force was lost. During the Civil War, Montpelier was owned by Frank and Thomas Carson, Irish brothers with banking interests in Baltimore; the house was not used as Confederate headquarters, but it attracted visiting soldiers, Frank Carson hosted a ball given by General J.E.B. Stuart, and he permitted the house to be used for a court martial in which seven Confederate soldiers were condemned to death for desertion. After the Confederate surrender in 1865, slavery ended across Virginia and the South, and former slaves were officially known as freedmen. In Orange County, thousands of former slaves sought work, often on the same plantations where they had once labored, now for wages, while land ownership became a universal goal among freedmen. Montpelier's Gilmore Farm became the homestead of one emancipated African-American family, preserving the experience of emerging from slavery and becoming citizens of the United States; the farm was settled by a freedman who had been enslaved by James Madison.