Hi all, I have just started playing CIV4 and have not developed a real strategy yet. I am just playing up the levels for now to see how each one plays so I can pick the one that works best for me. I am currently at the level of Warlord (yes I know I am a n00b

) and just have a couple of how to questions. It was my kids game originally so the book is long gone.
Welcome to CFC, Front. I hope you will enjoy our company.
1. How do you hide armies in a city? When I get to the last city of an opponent (AI), I have noticed that it occasionally hides units with high combat/defense multipliers from me till just before I finish them off, then it pops up 3 or 4 of these units. I would like to know how to do this myself, or even if I, can (without cheating)?
The computer isn't cheating, necessarily. The computer has the same ability as you or me to build units, draft units, and rush units. Naturally built units will pop up between turns so that accounts for one. Drafted units appear instantly, so that accounts for two. Rushed units (by universal suffrage or slavery) typically fall into the "built units" category. So, at least two of the units "could" be made from sacrificing resources.
Also, the computer tends to keep units in other cities and bring them in as reinforcements when it panics. If a city is surrounded, you ought not have this problem, just keep an eye on things hiding in the fog of war.
Additionally, if there are more than X number of units on a single tile, some units will inevitably be truncated from the bottom of the list and appear "stacked" that is, have a number next to them indicating that there is alot in there but not enough space to show them.
If you truly believe the computer is cheating, I suggest you ensure that auto save is on. When this phenomenon appears to happen, reload the auto saved file and run World Builder (or run it as a scenario?). From WorldBuilder you can literally see what the computer is doing, has done, and can do as if you were sitting in their shoes. If you can find the "instant unit" button, let me know. XD
2. Is it common in warlord (and up) that a friendly nation will turn on you when you are in the middle of a war with two other opposing factions? I was playing as Germany, and I was friendly with Catherine early on in the game. Alexander and Napoleon were constantly declaring war on me together and eating up my resources. Russia would honor the defensive pact and declare war on Greece but never attack (I was always left to deal with France on my own). Finally when I was down to five cities and meager resources, Russia ended the pact and declared war on me as well (in one turn she went from friendly to furious). Needless to say, my resignation followed quickly, lol.
Certain leaders can be bribed into going to war. The further behind they are on technology (or gold?) the higher the likelihood of your opponent being able to drop a fat stack on your friend to backstab you. Try not to let your friends fall too far behind. If you are the tech leader, keeping your friends close keeps them from going to war voluntarily and also keeps rivals from having the resources to force them to betray you (double benefits since AIs ask for higher prices to betray closer friends).
AIs don't attack if they aren't prepared for war. I can bribe Alexander all I want and he will start cranking out the units, but until he is good and ready, he'll broker peace ASAP and take my techs without batting an eye. However, once he DOES have an army, he will often declare war voluntarily on his weakest unfriendly rival. Make sure that you are friends with the strongest and pick on the weakest. Just like in school, ya know?
Also, at any level, you'll find that its a bad idea to have smallest army or to lose at all. Once you start losing, winning is usually not going to happen. This is what I call "kneecapping." If I kneecap my opponent, he won't get up. He might get a one stack army one day that might threaten a border city of mine, but basically, if I focused my full weight on obliterating him, he's smoked. AI thinks the same thing about humans. If you have a small army, few cities, no resources, and aren't defensive packed with much bigger and stronger civs, you will be the target of choice. Dogpiling is not uncommon either. I have bribed AIs to war
for free when the nation I'm picking on is small and I already have an ally or two. Don't be that weak civilization. I always check Demographics to make sure my military is in or near the top 3 within a reasonable deviation. If someone has three times the army that you have, you should probably quit the game unless you are playing Always Peace, someone is going to eat you.
3. Final question... Is the aggressiveness of opposing nations random or are some more aggressive to certain nations than others? As Germany it seemed that Greece and France were usually against me. As India it seemed it was usually England.
Thanks and sorry for the noobishness of these question.
I do believe some civilizations have hidden predispositions. This usually amounts to only a one or two point difference though. If you warmonger (get Civs to DoW on each other) then you'll usually find that the AI can take care of killing themselves. The AI, however, either have a natural tendency for war or for peace. Peace civs typically don't go to war unless you display GREAT weakness. War Civs are pre-disposed to wanting to "study on killin' you" and you really have to work to keep them from doing so. Making someone else their target is one of the easier ways of accomplishing this.
If you are an inexperienced player, this can be alot to take in. There are tons of resources here for you to look into. Big tip in your case is to build a big military and don't let them declare on you, declare on them first. Well thought out invasion almost never loses below Noble difficulty.