To the person who asked if she lost her arm in the end: No, I think it was only broken. You can see her arm in a sling (though it might appear slightly deformed to some people, so I can understand any confusion) at the end when she broke down and cried.
another way of beating the 300 into a pulp : max quake box + max grenade launcher + missile tower (upgrade as much as possible) + spend the rest upgrading the wall, and use leftovers on repairmen. "Fire in the hole..." :D