Thoroughfare Gap & the Civil War

**NOTE: There is no physical cache at the posted coordinates. You must find the answers to the questions below to get the correct coordinates for the actual cache location. To claim a find you must sign the log. Second note: I have permission for the cache at its final location. 

This Mystery cache will take you to an area that had several Civil War Engagements, with the most significant occurring on 8/28/1862 known as the battle at Thoroughfare Gap. There are a few historical signs at the posted coordinates to learn more about this area's significance to the Civil War. Once you've found the cache, if time and weather permits, go for a walk/hike over at the bull run mountain conservancy and look at the old burned down Chapman's Mill up close (address for GPS to get to this area is 17405 Beverly Mill Dr, Broad Run VA 20137). If it's a hot day there are a few parts along one of the paths where you can go for a swim in the "Broad Run" river. Please note that, although the cache is available 24/7, the hiking trails at the conservancy have posted hours (Also dogs are not allowed on the trails - even if leashed).

• Parking / pull-off area for the posted coordinates are right off the highway at the historical markers (please be careful).

FINAL DESTINATION: The actual cache is located at the following coordinates:

N 38° 49.ABC  W 77° 42.DEF
(Answer the below questions to find the values for the letters above):

A=  The last digit from the year that Chapman's (Beverly's) mill was considered a "shell" 

B= The last digit of the last year that the Mill was operational

C= The  year that the Chapman's (Beverly's) Mill burned, minus 1998

D= Year that the Campaign of Second Manassas historical marker was installed/erected minus 1,921

E= The third most northern Regiment, under the command of General G.T. Anderson of the Confederate Army, during the battle at Thoroughfare Gap on August 28th, 1862.

F= The nearest perpendicular Road divided by 300

Check Sum = 21