Optional Interpenetration Rule
This rule may replace the one in Sect. 4.2 (page 37) if all the players participating in the game agree with it.
If a unit passes through any friendly infantry or cavalry unit, the unit that is moving must pay an extra inch of rough terrain for each friendly unit that is penetrated just before starting to cross through them, and may not start overlapping it if it does not have enough movement factors to finish the movement and pass completely through the friendly unit or units. After paying the extra inch of rough terrain, the movement can be carried out normally without further penalties. Artillery units and generals can pass through or be passed through any friendly unit without any extra cost.