Play as the West:
Beat the game as the East.

Battle Mode Option:
Beat the game as the East and the West. A new option that allows you to choose your battle mode will be unlocked at the main menu. Any previous battle may be fought, as either the East or the West.

Hints

-At the start of each campaign, go for a defensive approach.

-Gather your units and await enemy movements.

-Intercept advancing enemy units with long-range attacks (canonade/ballista).

-Attack enemy units with several units, using special-attacks first.

-Keep it going until the enemy unit is destroyed. Do not let routed units escape as they will reform. More importantly, when an enemy unit is defeated, your army's
zeal will rise allowing for more special attacks.

-Use "rally" to raise the zeal of your units when in battle, preferably on units with long-range special attacks.

-Check your unit's status regularly, retreat immediately if your unit is losing a battle.

-Try to limit the number of engagements, as to have a better chance of controlling the events on the battlefield. Use the L2 button to call up a map of the entire
battlefield.

-Only at the very end (2 or 3 enemy units remaining ) should you call for an Army attack, keeping the units with long-range attacks at some distance.

Thanks to Revolution readers Wes Howe and Espen!