Fire Emblem: Shadow Dragon/Chapter 16

The Battle for Altea "Still smarting from their bitter experience with Gharnef and the dark magic Imhullu, Prince Marth and the League regrouped and march south- home to Altea. Once Marth's kingdom had been beautiful, blessed with rich soil and clear waters; now the eyes tended to notice instead the barren farms; the ruins; forlorn stares. Marth vowed to free Altea from its torment without any further delay."

Preparation
Pick your best units as normal, trade around units and get ready for some fighting. Start the battle and start moving... but wait! First...

There are many houses in the area...

Begin
Now that is out of the way, we can finally get to the real part of the guide. Leave a group of units to deal with the few immediate threats, then move Marth and about three other strong units to the left.

When you get to the villages, PAY ATTENTION! You can only get one of the two units here. There is a choice between a paladin (to the left) and the hero (to the right). I personally like Heroes better so I chose that.

Then again, I don't recommend using these pre-promoted units, just pick one.

Anyhow, keep moving your units to the left. You can consider using Beck the ballista to attack the units in the middle island. At the end of turn 10, leave no unit alone in the area of the villages. Enemy reinforcements appear in the four forts above. You should probably split your party in two:


 * 1) The mass of your army is still sitting at your base.
 * 2) Marth and 3-4 others are near the castle (but I wouldn't attack just yet, let the reinforcements run out)

Let the four reinforcements charge toward the main part of your army. They should die relatively fast.

Two reinforcements should attack your small army. They also should die fast. I would recommend staying put and waiting until the enemies stop coming in (a little less than Turn 20 - note that they come every 2-3 turns) Barge into the jail on the east and talk to Xane with Marth...

Xane can transform into an ally unit and have their abilities, stats, levels, class, everything! After a few turns he will go back to his old self, but he is useful if you have a favorite character that you want to "duplicate".

Xane is his own special class: the Chameleon.

Now, all units but the boss should be out. Proceed with caution as the boss is dangerous.

After this, feel free to use the arena to level up a bit. Also note that you have should put the master seal you got this level to good use.

When done, seize the gate.