A cavalry unit is engaged to the front by infantry and on the flank by cavalry . . It fights in both direction as it turned to face the guys on the flank so the cavalry is engaged  fighting for it's live ...but being exceptionnal they fight well ..so could the infantry break off as the ennemy cavalry is " slower" in the sense that being engaged on the flank it cannot follow up ? ( we know that the real move capacity must be taken into account, terrain type being an exemple ) or could the ennemy  cavalry break off considering the the exceptionnal target is "pinned" by the infantry ? so has a 0 move . We could go even farther and could both attacking unit disengage at the same time ? - you would need many good cards     -

No can't break off as not slower, just busy.

F4. Speed = when in combat (to deal with FoF only) and terrain.

Better to have said "as affected by terrain and excluding FoF" perhaps.
Hindsight being a lovely thing.

Si