I had Shale, Leilana, and Loghain (my guy was a mage). So my party was certainly not set to optimum conditions. Had to use Leilana as an archer, but never once used her as a ranged character the whole way through, so she ran out of arrows quickly then luckily just followed me around and fixed the ballista's for me when they needed to be repaired.

Also I never really gave much to those party crates at camp so I guess my armies I called in weren't up to par either. When I beat it all I had to call in was the humans though to take care of the minions. It was definitely tough, but the whole game in general was so thorough I expected it to be somewhere in that neighborhood of difficulty. If I can ever make it all the way through again I will be more prepared. Haha.