I managed the achievement last night on hard for the Destroy 12 Castles achievement. Took me a few tries and a lot of saving.
As soon as the scenario starts, save the game. Pause. Build two TC and get the remaining vills to build houses. You need to boom for about 15 minutes to build up the resources to press the attack. Once you have two TC up, build a third and aim for about 25 food, 25 wood, 15 gold and 4 stone vills. Your house building vills should eventually branch off and build the university/blacksmith etc.
First, send all your infantry south across the shallows towards Cyan. Kill the tower covering the crossing for later. Once you get out of being housed, send a vill across the shallows to cyan’s base. Your troops need to protect cyan’s trebs for the moment. Trigger the yellow attack with your scout.
Important thing to do, is build three strike forces. Cyan should be able to kill a castle alone. Your vill that was sent around, build a castle in rome just inside the destroyed gate. Research conscription when built and start building trebs. Vill should build a barracks, monastry and a barracks. Add other buildings if necessary (some cav is nice).
When you have two trebs here (it should be around 13/14 mins, you need to get smashing. With your starting troops, move west and kill the two castles. You should be able to kill these two without fighting anyone. This group will need to move north and kill two of the castles in the north west, one after another.
Whilst this group is on the move, start training 2 trebs and 3 monks. Start training huskarls and a few pikes. When you have 20 or 30, push onto the bridge and treb the castle down. Huskarls can fight the blue troops under the castle. Kill the castle and push across the bridge. There is a small hill just north west of the small island castle where you can treb two castles down. Keep training huskarls, cavs and pikes now. You should be getting loads of barracks in Rome now so it’s quick. Purple will keep attacking. Once you kill the two castles, move north and treb down the final castle. Keep spamming troops because there seems to be a trigger that make purple attack you here.
Meanwhile, in the East, at 19 minutes, you should have enough stone for a second castle. When you do, move into the gate destroyed by yellow and build there. Once built, build barracks. 5 huskarls with the castle is enough here. Treb down the castle across the river (if yellow hasn’t destroyed it). Treb down the castle nearest your starting location next. You can get it from the trees near your castle. Whilst you are trebbing the first castle, build two more trebs and treb the castle just to your north.
It’s very tight for time but you should be just able to do it. Good luck, it’s the best challenge in the game that I’ve completed so far!
