Above is a map of Camp Jackson after its capture by Union troops in 1861. The map comes from collection of the St. Louis Mercantile Library and appeared in a brochure entitled Special Collections for Researching Civil War History.
What I like about the map is that it gives a sense of the open space that was available around Compton Avenue during the era. This open space was being used as a baseball grounds in 1866 by the Veto Base Ball Club. The Veto Grounds, as it was known, was also the home grounds of the Empire Club that season. In the 1870's, Thomas McNeary built the Compton Avenue Grounds on the site.
I've talked several times about the amount of land around St. Louis that was available for use as a playing space for baseball and the effect that this had on the growth of the game in the city. I think this map does a good job of presenting that idea in a visual manner.