The discussion of this topic is the utilization of splash damage from weapons to attack targets that are submersible. Within the game engine splash damage is calculated as a sphere with the center of the sphere residing at the point of the weapon impact. Therefore damage inflicted can be at, above, below and next to the point of the weapon impact, say at the water surface. The range of splash damage varies according to weapon types, so it is best to consult Unit roles in various combat theaters & abilities to know which units can perform these abilities and then refer to the Complete unit list to gain the specifics. This tactic is especially useful when it is difficult to advance, defend against, or gain a foot hold in water due to the presence of submersibles (submarines, torpedo launchers, underwater experimentals, etc.). In addition, many of the units to attack the submersibles with this method have long ranges so as to clear the opposition without too much risk to your own units.
There are a number of ways to go about this, but let us start with the straight forward method. The first step once the unit or units are selected is to change the weapon firing mode to ‘Attack Ground’. Many units are set with the default ‘Fire at Will’. To change this mode by using your mouse, select and hold down your mouse button and a small menu will appear with 3 choices: ‘Fire at Will’, ‘Hold Fire’, and ‘Attack Ground’. Select ‘Attack Ground’, then choose ‘Attack’. Now select a location above the submersible to attack. You will notice that when you try to get near the target, the cursor will snap to the target and show you the ‘Cannot Attack’ cursor. This can simply be corrected by placing the ‘Attack’ cursor near the location. Next, hold down the shift key and move the ‘Attack’ command above the target. If the target is at the right depth, you will notice it taking damage. You can perform this same action with a number of units and each select their own targets. The down side though is that your units will continue to fire at this one spot even after the enemy unit has been destroyed. So you will need to either select another target (using shift drag the ‘Attack’ command), hit ‘Stop’ in the order panel, or change the firing mode.
Another method that provides more flexibility is selecting a single unit to perform the attack and then select other units to assist the first unit. This way you can concentrate your fire on a target and easily be able to break the order on the support units and they will fire as usual. You can use a stationary or mobile unit as the parent unit that assigns the ‘Attack’ command. You will still need to micromanage this but it is a bit more flexible.