Fire Emblem: Shadow Dragon/Chapter 6

Fire Emblem ""After shattering Medon's main force outside Aurelis Castle, Marth next led his army into the castle's halls to liberate the kingdom. A number of treasures slept in Aurelis Castle's nooks and crannies but how to extract them before they could fall into enemy hands?""

""Only a thief could open chests locked that tight," grumbled one of Marth's men.""

""But we don't have any thieves with us. ...Do we?"""

Preparation
Re-class Wolf from the previous level to a general. If you do so, Wolf will turn level 20 before you know it. He can also use the two legendary weapons, Parthia and Gravidus. This battle is going to be fast-paced, with no time for idling. Take your best units, get your best weapons. For the first half of the map, let your strong units rush and kill the various thieves before they run off with the treasure.

Keep some units for the latter part; you can afford to take your time after. Remember to take a thief also. There are no houses in this map.

Begin
Start the battle when you are done. First, do note that there is a thief locked in the jail at the beginning of the map. Don't waste time on him now. He can be recruited with Marth later (don't worry, he isn't going anywhere).

Rush the halls with your fastest units, i.e. Cavaliers. Back them up with Marth, Nabarl, Wolf/Gordin, and Merric. Make sure that no thieves even get close to getting away; the treasure is really good, especially the seraph robe.

Or, you could use warp and send Caeda to bar the exit for the thieves. Have her kill the cavalier with the silver lance using the wing spear. after that just have her kill any thief that comes near the exit. This will almost never fail.

At the bottom, near the throne, it is pretty packed and you will lose a character if you aren't careful. An easy way to beat it is first, lure the units one by one. Eliminate them then lure another. Once you can't do that anymore, while not risking losing a character, amass a small army. Figure out who is going to attack what.

For example, if you see two archers and a knight, you should think:
 * 1) Your mage, Merric, can easily take out the knight, so position him to do that.
 * 2) Archers can't fight back in close range, so get two cavaliers to kill them.

The boss is a pushover since he doesn't have any long range weapons. Use magic to beat him fast.

One thing I've also figured out. Is you can have any archer (if they can deal any damage), keep on attacking until they reach whatever level you want them to. But, you will need a lot of bows. This also works in other chapters where the boss can't attack at long range. This makes it easy to get a horseman/sniper. Using javelins and hand axes, However, it is more expensive. Watch out for critical hits on the boss (make sure he has enough hp left to survive a critical hit and a normal hit). If you do accidentally kill him, don't worry, there will be more.

After this, make sure you recruited Rickard in the jail, then seize the throne and save the game. Note that if you have 15 or less units, you will go to ../Chapter 6X/ – see Gaiden chapters for more information.