Quote Originally Posted by Titus Marcellus Scato View Post
Naval battles in EB are handled via auto-resolve. Auto-resolve gets more difficult the higher the campaign difficulty level is.

On Medium campaign difficulty, you can usually win with a 1.5 to 1 numerical advantage in ships over the enemy (assuming equal experience).
On Hard campaign difficulty, you need at least 2 to 1 numerical advantage in ships over the enemy to win. Or an equal number of ships one tier bigger than those of the enemy (e.g. they have Pentekonteroi, you have Triereis).
On Very Hard campaign difficulty, you need at least 3 to 1 numerical advantage in ships over the enemy to win. Or an equal number of ships two tiers bigger than those of the enemy (e.g. they have Pentekonteroi, you have Quadrireme).

This is another reason I play Medium campaign difficulty.
I'm not certain about the numbers you've written down, but in general you're right - campaign difficulty has a tremendous impact on naval battles, and you must have clear superiority to win them consistently.

Other than that, I've noticed that quality is better than quantity. Several times I've seen fleets of mine with above-average ships like Tetreres beat HUGE fleets of pirate ships, even though the pre-battle screen indicates that the AI had an advantage.

Command stars also seem to have an imporant effect on auto-calc in general. For this reason it's good strategy to hunt any pirate fleet you see into extinction, even if they're not bothering you personally, because it will give your admirals more stars and therefore better chances in "real" fights.