I recommend splitting your forces evenly with archers and cavalry both in the swamp and on the plains. Light squads should go to the swamp where ambush tactics are possible. The enemy forces have a number of rogues in their squads, so engage on player phase to prevent back row attacks & ambushes on enemy phase. MC can reach the goal from either the swamp or the plains easily enough, but the spread out nature of the objectives in the swamp leads me to prefer MC in the plains to allow the five units in the swamp more time.

You will have the chance to hire a light infantry mercenary squad here for 3000 gold. While this squad is immediately useful for ambush attacks in the swamp, you can get them for free a few stages later. Once you wipe out the closer enemies tactics will simplify to engaging on the rogues and avoiding leaving weaker squads exposed. There’s one last wrinkle: two groups of four mounted squads will appear from the east around turn 7. They are not particularly stronger than the other enemies here, but could surround an isolated squad if you are not prepared. You can defeat them for more xp and a chance for item drops or just bring MC to the blue arrow to finish the stage.

Interlude

You should be able to field 10 to 12 squads now and your very best characters might be close to a tier 3 promotion. This likely will take some shuffling of resources from the exchange, swapping elemental affinity around and even using some stat up items. While you should only use these limited resources on your best characters, definitely use them sooner than later. The spike in power for tier 3 is pretty significant & will help you gain even more funds while taking fewer losses.

I’d suggest priority go to promoting soldiers to sentinels to maximize survival, but if you are playing without perma death, you could try some zweihanders and centurions. Champions are likely out of reach for now (requires 47 strength!) unless you can hire one as a mercenary. Priestess to templar is the best use of sunstones, but you likely will be able to advance acolytes to paladins/valkyries first. You can always demote those later when your priestesses are ready for promotion & reuse those sunstones.

Here’s how my squads ended up after hiring an ice mage for Stefan’s squad to help skew skill based matchups in their favor. I added one more cavalier into Barnabas and Sir Rolante’s squads and promoted a few soldiers and acolytes to shore up the front line.