Hello Archon,

Why would I want to choose any unit based on anything but how cheap it can be produced and how much damage it can deal?

Some heavy infantry, phalanx, and mounted offensive units have varied levels and types of defensive strength but no matter what if they get attacked and forced to defend they get annihilated.

Where is there any strategy involved in building my army?

I always assumed spartan hoplites would fare better against attacking defensive light infantry and myrmidons would do better going against other heavy infantry. 

I assumed a carthaginian horseman with their balanced defensive stats would have better survival rates in battle to compensate for the lack of damage dealt compared to agemas. 

Some would point to speed as a desirable characteristic but I boost for almost anything taking more than 5 mins away. To me it's irrelevant. 

It is a certainty that Plarium could have explained this better. When I started playing the game, I also thought the same as you - the defense stats of an offense unit somehow influences how many of those offense units die when they attack. (Some sort of balance, in that offense influences how many they can kill, and defense influences how many of them die.)

When you are attacking an enemy, the only thing that matters in the outcome of the battle is the following:

* The offense of the troops you are attacking with and what type of troops those are.

* The defense of the troops that you are attacking, and how their defense scores are spread across light, heavy, phalanx and cavalry.

Obviously the bonuses to offense/defense that can come from many things play a key role too to buff up the scores mentioned above.

When I started playing the game, I also thought the same as you - the defense stats of an offense unit somehow influences how many of those offense units die when they attack. (Some sort of balance, in that offense influences how many they can kill, and defense influences how many of them die.)