SUSAN: The permanent Fairfax County Courthouse was finished in April of 1800 and was a center of activity through the end of the Civil War.

The very first land engagement took place around the courthouse on June the first, 1861.

Once the Union forces had control of this area of Fairfax, they did take over private homes.

An example of that would be the Willcoxon family home that had just been built in 1859.

The family had left to seek shelter with relatives in Loudoun County.

ANDREA: When the Union soldiers came into the house, it was an abandoned house that had bare plaster, and they left their pictures, their sayings, their names, their regiments, all over the walls of the house.

It is an amazing thing that helps us learn about the soldiers.

The family knew there was graffiti in the attic because they never covered it over.

When the city purchased this property, on the first and second floors, the walls were covered with wallpaper and underneath that, many layers of paint.

And so we proceeded to look for more graffiti underneath those layers.

But there were some areas where they couldn't remove the paint.

And so that is when Mike Toth was brought in to find soldiers.

MIKE: We illuminate the walls just with narrow bands of light.

We put all those colors of the rainbow on the wall individually.

And then we take a picture.

We combined those using a statistical algorithm in a very powerful computer to help Andrea and other researchers identify the information they need.

ANDREA: For years I was wondering who Stephen W was.

All we could read on this wall was Stephen W and then began with an M and ended with what I thought was a Y. Mike handed me the images on the computer.

I could take that black-and-white photo, that was the one that was most distinct, blow it up, and put it against a Civil War database, and that was how I was able to track down Stephen W. Millichamp.

It was very exciting to put a face to the name.

Our soldiers are really a time capsule.

Here are their names that have been on the walls of this house for 160 years.

It really brings a very human element.

They aren't just writings.

They are true human beings who had been here.