TBC Walkthrough
Introduction
[WHU]
Farborough
[WHU] In this scenario, you will be facing enemies far superior to yourself. You will constantly be ambushed, so always leave yourself plenty of movement points to retreat, there's no turn limit. Just to the north is an obelisk, known as a Waypoint, move a unit onto it to learn about it. Unfortunately, it is key to surviving this scenario. Keep a unit next to it at all times so that if one of your units is in danger, you can transport back here, with all of your units healed and cured and the townsfolk regenerated. And that's what you'll need to do, trigger an ambush (with plenty of moves left), attack and try to kill someone for XP, then step on the obelisk and reset. It's kind of lame, but it's that or a lot of save-loading.
[WHU] Sometimes when you kill an enemy, they will offer to join you. I know of no instance where this is a bad idea. Note that Rimaru heals +16, which will come in handy. Try to advance anyone with leadership as soon as possible. Take your time, make your way north.
Crooked Ravine
[WHU] If this is your first time on this map, leave someone at the start, so you can retreat when in danger. Proceed slowly north to make contact with the Waypoint. When you get near the north you will trigger the Brothers of Light. To defeat them, you must kill all three mages. Chances are, that's not going to happen the first time, or the second... You'll probably end up fighting their army several times, using the river against them and running away via the Waypoint while collecting XP and gear.
Punishers
[WHU] No more running away, this time you have to fight. And win. And with a really tight turn limit. Hopefully, you leveled up a leader or two, because you're going to be recruiting woodsmen and peasants. Lots of them. Make use of your leaders and healers to support them, and try to make sure that you are constantly moving forward. Most of the time when you level up a woodsman you'll want to choose poacher (you can recruit bowmen, but not poachers, in the next scenario).
Burke's Retribution
[WHU] Use terrain, and a constant stream of fodder, to offset the enemies' numerical advantage. While the enemies are trying to overwhelm you, send a hit squad or two around them to assassinate their leaders.
[WHU] When complete, you will find yourself back in Crooked Ravine. Simply travel north, behind where the Brothers of Light appeared you'll find the passage to Goonville. There's also a cave along the upper right side of the map with a few undead, hopefully Rimaru is at least a Mage of Light by now and can make short work of them. At the end you'll find a pathetic chest of gold.