You can find the army camp by opening the barracks and going to that tab. If you see that you have, say, 10 squads of light melee, that does not mean you are able to put all 10 squads into one battle. It does, however, mean that you have the opportunity to go into a second battle, or to try again.
Also, hover your mouse over the troop type in the army camp (PC version only). There it will tell you the number of single units you have that make up that number of squads.