As others have been saying, not much canon information about the 4th Frontier War. You could make the (not unreasonable) assumption that Imperial Marine units stationed in the Marches were the same as those in the 5th Frontier War a few years later.
In that case you could choose from the 1931 Regt, the 2091 Regt, the 5722 Regt, the 8327 Regt, the 1071 Regt, the 8041 Regt, the 3277 Regt, the 6127 Regt.