Well I usually play Despotism for most of the game... until I conquer the world that is. Using militia, chariots, etc, I have managed to defeat civs that have had bombers & tanks. It's simply a matter of volume.
In despotism, you get free support for a number of units equal to the number of the city. In Emperor, a city with two defense units can grow up to 4 without needing a temple. This is ideal; I just build lots of these small cities... decentralization! So each of these cities can support its two phalanxes plus 2 more units for free. If the city has a production, say, of 6 (which is typical in such small cities of mine where the growth has been stunted intentionally @ 4), then that city can support its own defense plus 8 units. This is plenty. I go into war with at least 6 of these cities, which means I can support 48 units max. Sometimes, when using 15+ cities, I have had over 200 units (not including defense in my cities). That is an unstoppable force. Sure, half of them are militia, but they just don't stop coming. I've had a line of units leading all the way around the world, following the path of my conquest. They just walked single file down this road that lead to the battles, taking triremes (ferries) accross small gulfs and destroying everything in their path. On one game, I was delayed getting a trireme to the final spot to launch an attack on the last civ. By the time the trireme got there, the pile of units had built up 150-160. The strait was very narrow, and I was able to land all the units in one turn. The civ I was attacking had 3 cities, none of which were larger than 6. Needless to say, they didn't last long. I had enough units to cover the continent, twice, plus a steady resupply flow on the way.
My point? Support is not a problem. I always have the resources to support militia. IMO, when at war, 20-30% of a city's production should be devoted to unit upkeep. If it is less, you are building units that are too expensive. If it is more, then you are either building units that are too cheap or you are not using your units aggresively enough.
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