1865 Southern Maryland road and town map.

[mike86002000]

Parson Wilmer was generally well known in Charles County. At a time when supporters of the Union and Lincoln were despised, and few in number, he made his sympathies known. I think he was very courageous. Booth and Herold would have gotten no help from him. I think it was Herold's bad joke to imply they would seek refuge there.
However, note the very direct road from the church to Port Tobacco. If they had found St. Paul's, and managed to avoid Parson Wilmer, Booth and Herold would have been "home free" to familiar territory and friends.
If Booth and Herold did indeed leave Dr. Mudd's following his directions to "Parson Wilmer's", as he told Col. Wells, the Dr. did not attempt to misdirect their pursuers. It undermines part of the case against Dr. Mudd.
The old map I mentioned above showing Booth's escape route through "Brice", was included in a pamphlet printed 10 or 15 years ago, although the author seemed unaware of it. He was a firm believer in the escape route East of the swamp.
I found a modern map that still shows a bit of Brice Chapel Road. It's the end at 488, between Piney Church Road and Rt 5. At one time, I think it extended to the area of St. Paul's. I don't know where, exactly, Brice Chapel was. I think it had disappeared by the 20th century. https://www.bing.com/maps?q=st+pauls+chu...o=Moderate .
Mike