Tactics for the Swamp (Fortress).

Well, I also play Heroes a lot, and mostly against bots. So, any online player will beat me with any Castle, including the Swamp. And that's despite the fact that I don't consider the Swamp to be weak. So, it's better to play online first, see how strong opponents play, and make sure that the Swamp is no worse than other Castles. ;)

I definitely believe that an online player could beat me. :-)

But I still think that the Swamp is generally weaker than the other Castles.
Of course, if the map has nothing but wood, then the Fortress is unbeatable. But that's just a specific case.

For example, I recently played on an island map (XL).
I placed a Castle - random.
I got the Swamp. The only advantage was that I immediately recruited a Voyager with Navigation.
Yes, I built up quickly, but by the time I sailed to the enemy, they had a quite defensible army. Since the opponent was a dumb AI, I, of course, defeated him, but the point is that after I took two Castles, I started recruiting units only there (well, I sailed home a couple of times for Hydras and Gorgons :-)) and I can definitely say that, for example, a 2-week army of a Castle and a Swamp is "two completely different things." If the Swamp units were heavily decimated by the opponents, then the Castle, after a battle with approximately the same forces, came out practically without losses.

In general, my conclusion: The Swamp is great in fast games on small maps, and the Great Gorgons are awesome; in skilled hands, they can do wonders. :-)
I almost fell off my chair when I saw how my 90 Gorgons attacked 15 Black Dragons, and I thought - now the enemy's dragons will retaliate and my Gorgons will be left with just horns and legs. The Gorgons attacked - 2 dragons and 9 units died from their gaze! It's a pity that there are no other worthy warriors in the army besides them.