To easily win battles with bridges, make an army similar
to the following. Have six to ten units of Archers or Cavalry
Archers. Have about three units of Yari Ashigeru. Have at least
three additional non-Archer Cavalry. Position all your Archers
close to the bridge. When all the Archer units are in place, send
a unit of Ashigeru to attack at full speed. Since they tend to
run away frequently, they will soon do so. They will come through
the bridge, making at least five of the enemy units chase after
them. This is when your archers Begin to fire and destroy many
of the enemy units. Do this again with the fresh Ashigeru. When
the enemy starts to run away, charge with your cavalry unit. This
should guarantee an easy win.