I notice that I can promote units within a city for no apparent reason. Such as warrior to axman or archer to horse archer. Does anyone have the logic behind these promotions and can you do it later in the game??

Minor wording convention: You are describing an upgrade not a promotion. Promotions come getting experience from winning combats, or from buildings like barracks, and allow you to improve the unit, without changing its basic type. Upgrades are made available by advanced technology. When a unit is obsolete due to a technological discovery (as a warrior is when you invent axemen) you can pay to upgrade your old warriors to axemen, so they remain useful. This occurs all the way up to the modern age, where it stoips simply because the most modern units are the last, and don't go obsolete as there are no more advanced ones. You can for instance continue to upgrade your axeman to a musketman, a rifleman, and infantry and finally a mechanised infantry, though it works out expensive in gold.

You can upgrade units anywhere in your own territory, not just in cities, as long as you have the appropriate resources and technology. (By the way, I don't think archers upgrade to horse archers, they upgrade to longbowmen or crossbowmen as you choose).

http://forums.civfanatics.com/showthread.php?t=135395

THanks for the upgrade info. But there are some warriors or archers I can upgrade and some I can not at the same time. I highlite a warrior in one city and it gives me a lighted axman while in another city it doesn't lite up and therefore I don't know how to upgrade. Appreciate any info. Thanks Webb

Guess in the cities where you can promote units you have a barrack and the units you can promote are just recently built units from these cities. And you don't have barracks in the other...

THanks for the upgrade info. But there are some warriors or archers I can upgrade and some I can not at the same time. I highlite a warrior in one city and it gives me a lighted axman while in another city it doesn't lite up and therefore I don't know how to upgrade. Appreciate any info. Thanks Webb

You probably don't have enough gold. It's fairly costly to upgrade a unit in the game, most people only do it to their most advanced units and either delete the rest or use them as cannon fodder in a battle.

Guess in the cities where you can promote units you have a barrack and the units you can promote are just recently built units from these cities. And you don't have barracks in the other...

You don't need a Barracks to upgrade in Civ 4. In fact you don't even have to be in a city, you can do it anywhere within your cultural borders as long as you have enough gold.

You also need to have access to the right resources, so if the Warrior in City one is dis connected from any copper or Iron sources you have it can't be upgraded.

Yeah, what Krik said is right.

You can only promote a unit if the nearest city has access to the resource. You must also be within your own territory. A barracks is not necessary for upgrading, you just need to be within the cultural influence of a city which has access to the required resource. Meeting these conditions will give you the option to upgrade. If you lack sufficient gold, the upgrade option will be darkened-out and unavailable.

The cultural-influence thing I tested, I had a warrior near a city w/o copper and when I moved him south towards another city, the upgrade was then available. The warrior was within my cultural borders at all times.

Oh, and archers don't upgrade to horse-archers.

You can only promote a unit if the nearest city has access to the resource. You must also be within your own territory. A barracks is not necessary for upgrading, you just need to be within the cultural influence of a city which has access to the required resource. Meeting these conditions will give you the option to upgrade. If you lack sufficient gold, the upgrade option will be darkened-out and unavailable.

Another condition:

No one has mentioned yet that to upgrade, a unit must not have moved yet in its turn. A unit uses up all its movement points when it upgrades too.

This may have been why you could see some units that could upgrade while other units of the same type couldn't. For these units that have moved, the option to upgrade won't just be greyed out - it won't be there at all!

That's not exactly true. A unit can upgrade after using some movement points, as long as it hasn't used all of them. In fact, i usually try to move units their max distance minus 1 when upgrading to make full use of this fact.

That's not exactly true. A unit can upgrade after using some movement points, as long as it hasn't used all of them. In fact, i usually try to move units their max distance minus 1 when upgrading to make full use of this fact.

I stand corrected. It's the airlift command which needs units not to have moved. Silly me.:crazyeye: