Hmmm...it has been a while since I've played. Does the river angle some to one side? If so, you might try to exit to the next map with all your guys at both banks of the river and see if they would then show up on the same side on the next map. I'm sure it can be done, because I do remember having that problem and getting it solved. Just can't remember the exact details of what I did.
Figures...Can't find the CD...got the case, but ain't no CD in it. We moved a few months ago, and my 'computer room' is smaller than what I had, so a lot is still packed until I need to go looking. I'll find it sooner or later, but for now, I've struck out. Sorry about that...