Battles are where a major aspect of the game comes into play: veterancy. Just like you level up characters in RPGs by having them fight or do other tasks, you can do the same for all of the units in BFME. With 4 levels total, higher-level units are better at fighting in many ways, making them quite an asset in having to react to various events that go on in a game. Upgrading your units has similar effects to gameplay, as you have to upgrade individual or groups of units, not every single unit on the map. If there's a breach in a fortification, you might want to send your high-level, well-upgraded troops there to hold back the tide of lower-level troops for a while, or you may decide to save them for a direr situation.

While regular units have 4 levels, heroes have 10. And as you would expect, Heroes are insane in battles; they pack quite a punch and can take a whole lot too, especially if they're leveled up. Higher-level heroes are just as effective in the game as they were in the movies and books; if you've got Gimili, Legolas, and Aragorn at a wall breach, you should be able to keep it plugged-up for quite a long time.