The troops- Dec 2013

Troops can be trained in the Barracks, the level of the barracks determines how many soldiers you can have at a time. There are four types of soldiers: Infantry, Cavalry, Archers and Catapults. Each type of Soldier has it's own unique  characteristics. These are laid out very nicely in a table in the barracks information (little i in top left corner).

• Catapult's attack will increase by 20% when attacking a city.
• Infantry will do extra damage to Archers
• Cavalry will do extra damage to Infantry
• Archers will do extra damage to Cavalry
• The "load" is how much each soldier can carry back from a raid
• speed determines the marching time
• Crop cost determines how much food each soldier eats per hour at rest in town
• Crop cost while marching determines how much each soldier eats while marching.

So as you can see Catapults have by far the most life when fully enhanced, but Archers have the highest attack And Infantry have the highest defense.