First Things First:

The memorial below is Confederate Mound at Christ Church in Alexandria, Virginia. It was built in 1879 when the Southern Memorial Association moved the remains of 34 Confederate prisoners of war from Alexandria's Soldiers' Cemetery, a federal cemetery. Take into account the words inscribed on the plaque at Confederate Mound, who arranged for its creation, and who is buried there to get a sense of the purpose of the memorial. Click on each magnifying glass to learn more about the source.

“Now sleep the brave who sink to rest/By all their country’s wishes blest” This quote indicates that the Confederate dead served with valor for their country and would be remembered for it.
"Southern Memorial Association" This would have been a group with an interest in preserving Confederate memory and the grave. This group would most likely be sympathetic to the Confederate dead and would recognize their deaths as noble sacrifices.
"SC (unit location)" Most of the dead were not from Alexandria yet were still memorialized there. A “Confederate” memorial, rather than simply an “Alexandria” memorial, shows an interest in memorializing Confederate dead as a national effort rather than simply a local one.
Think about it:

What can this gravestone tell us about the memorialization of Confederate war dead in 1879, when Confederate Mound was created?