Johann and Wilhelm always fight together as a unit of skirmishers and cannot join any other unit. Note that they are treated as a single man-sized character for the purposes of not being targeted by enemy missile fire.
Source: Warhammer Fantasy: 6th Edition
Johann and Wilhelm always fight together as a unit of skirmishers and cannot join any other unit. Note that they are treated as a single man-sized character for the purposes of not being targeted by enemy missile fire.