Groundhog day question?

[Liebchen]

Broken units retreat when fired at by direct fire.

Though technically the road stacking limit is violated by the move across the bridge, I guess you could think of it as units moving one after the other. In this case, they still used full MP's due to moving ZOC-to-ZOC into a hex held by friendly units. Normally, Disrupted/Broken units can't make a contested bridge crossing (ZOC-to-ZOC across a bridge) if there's no friendly unit in the destination hex.

Just realised something.......the units trying to cross the bridge are all FOOT units. Doh.

I don't see how that makes any difference, since road movement limits apply to all units using road movement.

I think that you're seeing the forced bridge crossing rule in action. It does not, technically, use road movement, but does use the entire MP.