Mass Combat

[Michele]

Originally Posted by Peter Knutsen

I had low-TL armies in mind. My impression is that apart from the armies of great and very organized empires, such as the Romans and Persians, most TL1-3 (and 4 too?) armies consisted mainly of one troop type, either archers, or infantry, or cavalry.

I'm not sure of that.
The Greek city-states weren't a great and organized empire, and the big chunk of the army was definitely the hoplite heavy infantry, yes. But they had peltasts and archers as auxiliary light infantry, and later they began to field the phalanx.
Plenty of the various Italic people that Rome defeated in its early centuries had a hodge-podge of medium infantry, psiloi, left-over light chariots, and sometimes some horsemen.
The above also applies to the Gauls.
Various African powers who weren't necessarily the organized Carthaginian empire, but, say, the Numidians, added to all of that heavy infantry and of course elephants.
Most of the peoples who had an all-cavalry (or nearly so) army, would have both shock cavalry and light cavalry, and maybe horse archers.