Something that I would like to see would be more advanced orders that involve particular movement and teamwork relative to the enemy fleet, that I am calling maneuvers here. Ideally it could make battles more dynamic by giving fleets something to do other than blobbing together and retreating piecemeal. Different factions (and commander personalities) could prefer some types of orders over others.
For the implementation, it would require a couple additions to the AI: awareness of ships as groups, and prioritizing moving over attacking in certain situations (also useful for capture orders).
Ship Groups:
Spoiler
Artist's Interpretation of ship group UI
Ships near each other would sort of take up space around them depending on size, and that "personal space" would be blobbed together where it touches, not unlike some methods of rendering physics driven fluids in 2D. This allows a group of ships to be considered a semi-persistent entity, even if ships enter or leave the group (but can split the group if there is no ship to fill the area). Generally, maneuver orders would be given while targeting a ship, but the order itself would target that ship's location in the group.
Example Order - Flank:
For the flank order, you would target a ship at the side of a group to give the order, and assigned ships would move to the side of the group before engaging - moving to that area is more important than attacking en route, although if it can attack without risk and without needing to slow down and turn, that is allowed. Once there, ships would engage any ship in that location in the group, hitting it from the side (presumably the main battle line is hitting it from the front) and eventually folding the enemy formation in from the side.
Example Order - Breakthrough:
The breakthrough order is more complicated, as it has multiple parts and multiple roles. It only makes sense in a large battle setting of mixed sizes, where the battle has settled into two rough lines of ships wailing on each other.
Selecting a target in the middle of the group where you would like a hole to be starts the order. Assigned to the order would be one or more heavy ships to serve as hole punchers (hello, Onslaught!) and some number of faster ships (mostly destroyers/frigates, although fast cruisers could be included). The hole puncher(s) would attack any enemy ship in the target area to drive it off or destroy it, while the faster ships would escort the hole puncher(s) in order to help out, but more importantly be nearby.
Once a hole has been achieved, the fast ships would cease escorting and instead move into/through the hole as possible so that they can engage the enemy from behind while the battle line is broken. Again, moving into the attack position is more important than actively attacking, because the goal is to get (semi-)safely to a position to hit the enemy from multiple sides. Just like cavalry breakthroughs in real life, some losses may be taken moving in and reinforcements can make this risky for the units moving through the hole.
