The first burials of Union dead at Arlington happened in mid-May 1864. Coinciding with The Wilderness Campaign. I doubt Lee ever looked over his shoulder at his wife's ancestral home and shook his head at the fact that Union dead were buried on the property. He didn't have time. He was filling plenty of Southern ground, now designated as cemeteries, with plenty of Union dead. Our state is filled with Yankee soldiers' bones and blood. Along with thousands of Southern heroes and martyrs. That's what makes Hanover tomatoes grow so good.
The best Arlington website is.....http://xroads.virginia.edu/~cap/ARLINGTON/arlington.html
Keith