Unit size and campaign difficulty

Changing the unit size used in the campaign modifies it's difficulty.

This is of course blindingly obvious once you realise it, but it took me a little while and I haven't seen it noted elsewhere on the forums.

This has two components:
1. Higher unit sizes advantage the human player because the player typically builds fewer units, uses them more efficiently and takes far fewer losses than the AI in battle. This means that human towns lose less growth to the army.

2. Higher unit sizes advantage the civilised nations because they have (or at least can reach) greater base populations and can better afford the manpower drain. I suspect those players who are capturing 500 pop developed barbarian cities are seeing this effect - a city of 6000 that is building a 240 man warband every turn needs to be growing at 4% just to break even.