Fortress is a neutral alignmenttown with the beastmaster and witchhero classes. Fortresses are built at the edge of swamps. Their armies are primarily made up of deadly creatures – born of the swamps, and then subdued and trained for warfare. Fortress represents Tatalia.
Their swamp native terrain makes them move much faster than any hero (without pathfinding) in the swamp.
The Wyvern Nest is very cheap and has very low requirements compared to the other level 6 dwellings, allowing the Fortress town to get level 6 units in their army early even on impossible difficulty.
Bron is the only hero in the game to bring level 4 units - Basilisks - with him at the start of the game. (Except Illor in HotA.)
Cons
Fortress creatures have the lowest attack ratings of all towns.
The heavy focus on Defense can be disadvantageous in many cases, as a hero with high attack can kill their enemies before they have a chance to attack back. Attack can therefore be used as a type of defense, while defense cannot be used as offense.
The heavy focus on Defense combined with the fact that fortress only have got one shooter makes it more difficult for fortress to win battles without casualities than the other factions.
Some creatures have poor stats (in Shadow of Death some stats for Lizardman/Lizard Warrior and Serpent Fly/Dragon Fly were increased, but overall they are still relatively weak. In wake of gods, this can be fixed by use of some settings making Fortress creatures better).
Very slow 7 level creature, especially the basic version (with speed 5, Hydra is slower than six lvl 1 creatures, and there is no upgraded lvl 1 creature slower than Hydra; among lvl 2 melee units, only Dwarf, Walking Dead, and Zombie are slower).
With two relatively weak fliers (lvl 3 with 20 hp, lvl 6 with 70 hp) and one very weak shooter, the Fortress has a very hard time invading other towns properly. So Expert Ballistics, Expert Teleport and/or Expert Earthquake are a must.