Credits: Memento Mori
Simply said, when a unit stands on a certain type of footing, a dodge bonus is given, as well as a possible restriction. Note that this section does not apply at all to castle units.
River/Sea: -30%, can only be crossed by pirates. Movement/5
Road: -10%, movement+1
Desert: -10%, Mounted Unit Move/4, Heavy Unit Move/3, Normal Unit Move/2
Bridge: -10%, +1 movement
Gate: N/A; Recovers 30% HP if guarding castle
Woods: +20%, Mounted Unit Move/2, General Unit Move/2
Mountain: +30%, cannot be crossed by Armors/Unpromoted Mounted Units
Forest: +40% for Bandits, Movement/5
Peak: Unable to be crossed.