Hello 

I've discovered that an AI will make extremely poor choices in certain coastal battles. The context here is that, on turn 200, I had declared war on an AI whose empire was on the other continent. I had already sent a few armies - along with naval escorts - across the ocean in preparation for an invasion. This AI was my main rival for score in the game, and it was technologically ahead of me. I expected a difficult and costly war. However, after I moved my three land unit armies to the northern coast on turn 203 (intending to disembark them onto land the following turn), the AI decided to attack from the shore, right at the beginning of turn 204.

At first sight this could seem to be a strong move because at this point in the game all the land units were gunners. With ranged attacks, the AI army would quickly destroy my units while my units' combat strength was low due to being embarked. I would have been forced to retreat. However, I had two navies nearby, which were able to reinforce my units immediately. I realised that because my defending flag was on the ocean, I had the option to withdraw my units safely out of the 4 hex range of the gunners on the shore. Rather than keep its units in a strong position on land and allow a possible stalemate, the AI proceeded to embark its units each battle round, two at a time. Once the units were embarked, I immediately killed them with my naval units. The AI continued to do this every battle round, unable to touch my flag or attack my units due to the limits of embarkation, allowing just 2 of my ships to destroy over 20 technologically advanced land units effortlessly over the course of the 6 turns of the battle. 

Because my embarked land unit armies had been involved in the battle, they were unable to move after the conclusion. While my armies were still on the coastal water, the AI immediately sent a land army, with reinforcements, to launch another attack from the shore and begin a second battle. Again the AI repeated this process of throwing away a large number of units, two at a time, attempting to reach my flag in the water. While these two battles played out over 12 turns of the game, I brought additional units across the ocean. After the second battle, I was able to move my units onto land and capture the AI's northern city with minimal resistance.

The picture here shows the battle scenario halfway through the first battle:

I would suggest that the AI should probably not have attacked me at all in this situation. The optimal choice would be to wait on land and ambush my units when they disembark, catching them on the shore where they have minimal deployment area and my defending flag would be in reach of the AI's land units. The AI should have awareness that I had naval units in the area, as my navies had been in sight of the AI's units. Also, one of my navies had previously attacked and destroyed one of the AI's embarked armies off the coast of the island to the northeast on turn 201. Even if the AI is not able to take into consideration this kind of persistent military awareness, it might act with the assumption that naval support for the offshore defenders is at least a possibility. The AI creating a situation for their attacking land unit army where the defending flag is in the ocean can be very risky. Given the potential for naval reinforcement by the defenders, it is especially risky for the AI to launch an assault into the water if it does not have its own navy in reinforcement range, or at the very least land units with sufficient range to attack a navy of the era.

Even if the AI decides to start a battle with such a risky attack, it should absolutely not endlessly embark units to their deaths once there are enemy naval units present within the battle. At that point it would be best for the land units to remain on land (or return to land if they are already embarked) in a position of strength, even if it means a stalemate. The AI could then prioritise bringing a navy or long range land units to reinforce their side, if available. Once the enemy navy has been dealt with, the AI could embark units to take the flag, if necessary.

One final note, as the AI did happen to bring a howitzer into the second battle, which might have caused some trouble for my navy. However, I believe the howitzer's line of sight was continually blocked by the AI's own gunner units as they moved to the shore to embark. If the AI intends to rely on land units that could outrange the enemy navy in a situation like this, it should prioritise ensuring that they are both in range and in line of sight of their targets, if the units do not have indirect fire capability.

Please let me know if you need any more details. This situation felt very bad as the player, as it trivialised the war I had been building up to with my main rival in this particular game. The turn 203 save file Ethiopians Turn 203.ctr and the turn 204 save file Ethiopians Turn 204.ctr

Hi Ansatz !
Ow fuck, this is a big one (っ °Д °;)っ
Thanks for your detailed feedbacks, and also thank you very much for your saves, it will make the debug waaaaayyy much easier.

Thanks for your reply! I'm sure it is very complex to debug all the AI decisions!

I'm glad I could provide my feedback and the saves for this though. I'm a huge fan of the game, especially with the great updates so far. 

Excited to see how it develops  :)