I think the one I saw is the one Robert mentioned. The Peruque Bridge in St. Charles County was one of the longest RR bridges in MO and for that reason was one of the most vulnerable. This made it imperative that the northerners place one of the first blockhouses guarding that bridge. Well I was only one county away from the right one, but "a miss is as good as a mile." Thanks for your feedback, both of you.

Bruce Nichols