On the hellfire level where you start out as 4 stone throwers an ogre and a drummer put the invicability cheat on then avoid meeting up with your 'kinsmen being ambushed' it helps if you also use the fog of war cheat.

Now go staight to your buildings without meeting one of the several groups spread out on the map no go and make as many guys as you possibly can now you can go save your people and you should have sixteen units. (note; this only works on the forth level).