Hidden Cities - 1
This is a rather easy stage. There's one road between you and the enemy which branches off into smaller roads. The key is seizing control of the road before it branches off, so you don't have to post many sentries.
Move southwest from your base and take Gallstad, the nearest city, and the Temple near it. From there, move along the road from Gallstad as quickly as you can south. You'll come across Entel St, which you should liberate. Stay there and post another sentry in Glyng'Br, the city west of Gallstad, and maybe one more in Gallstad just in case. Send a scout to liberate the two cities to the far north (Suntsuba and Bosetyn). In Bosetyn you'll get an item which varies depending on your reputation.
By now the enemy should be attacking, with most of its force engaging Entel St. You'll face some Undeads as well as some Mages. You'll also encounter Dragoners, but they aren't very strong. Large tag teams of Ninjas are also present in this stage, but their front-row attack is pathetic while their back-row attack misses often.
Liberate Tronheim, the easternmost city, Olesun, the city southwest of that, and Zolmstei, the hidden city on the island south of Olesun. Seek out all the treasure as well. Between waves of enemies, move whoever is in Entel St south along the road to Belgen. Hold Belgen and you've pretty much stopped the enemies of getting anywhere near your base.
Eventually, the enemy will just run out of money and the attacks will cease. At that point, find the Chaos Gate. It's in a straight line to the far northeast of your base, in a clearing on a small, mountainous peninsula. With this done, move along the road from Belgen west to Drummen, just south of the enemy base. After seizing that, take the enemy base as you like.
Boss: General Figaro
He's really nothing special. His Darkness affinity is pretty high, so Light characters may be in danger from his attack. On the other hand, his White affinity is low, making those Light characters good to use against him. Use one or two Angels if you like, but really it's not necessary.
By now you should have a powerful magic team. Since you can get Undead Staffs in Diaspola, trade all of your Sentoul Demons for them and make your Mages into Sorcerers. Sorcerers get two magic attacks per battle each, and with that sort of firepower, Figaro shouldn't last very long.
If you skip this stage for a while and complete it only after Shangril, you can come here with Debonair in your party. That way you'll get Figaro's sword. Don't bother doing so, however, as you'll have found better weapons in the treasure spots by now.