Rome total War

So... I'm too lazy to read everything.
It's a great game, we used to play it online with a friend.
Now about the Spartans. You can't break through them, not even with cavalry, these bastards are invincible! We were playing once... I had a cliff on my left flank. During reconnaissance, I hid elephant units behind it. I see he bought some Spartan units and a couple of cavalry units. I immediately put the cavalry on spears, but I was afraid to attack the Spartans. And when they got closer, I brought out the elephants and attacked them from the rear. And guess what?! I almost completely (ALMOST!) destroyed one unit and damaged another, and there were tons of them! Even archers didn't help, these bastards don't fall down at all! However, I had the same situation, we were playing with the same person, and he was besieging my city. I put two units of Spartans in the passage and one unit of archers at a decent distance behind. He, of course, made a mistake and led everyone through one passage, and these three units wiped out his entire army, plus I had to send one more unit. Isn't that overpowered?