Turned Red: The Battle of Antietam (1983).
The books on Clara Barton provide incredibly moving descriptions of the conditions of the wounded at Fairfax Station and explain Barton's role in greater detail. I'd recommend reading these accounts before touring St. Mary's and the Fairfax Station area.
Additional Tourist Information & Sesquicentennial Events
Hyperlinks to the websites for Ox Hill Battlefield Park, St. Mary's Church, and the Fairfax Station Railroad Museum can be found in the main text above.
There are several upcoming Sesquicentennial activities related to Ox Hill and the aftermath of Second Manassas:
Ox Hill Battlefield Park will be holding an all-day commemorative event on Saturday, September 1, the 150th anniversary of the engagement. More information can be found here.
This upcoming weekend, the Fairfax Station Railroad Museum will be hosting an event to commemorate the medical treatment and evacuation of the wounded after Second Manassas. The focus on Civil War medicine and Clara Barton should make this an interesting event. See here for more details.
St. Mary of Sorrows is holding a candlelight memorial service in memory of those soldiers killed and wounded at Second Manassas and Ox Hill. Information on this unique event can be found on the church's homepage.