I have been playing Civilization IV for quite some time, and so far it is one of the best games I have ever played. Its deep gameplay is based on how civilizations survive, so strategies employed for the game, common reoccuring scenarios, and AI behaviours somewhat represent how governments of the world behave.
A nation with larger territory usually wins over the smaller ones---but only if it is managed well. The more cities you have, the greater the cost for maintenance. However, more cities mean:
- more productivity, and productivity usually means everything: troops, buildings, or MONEY. So you can have bigger military force, boost education and research, or turn one city to a money-making machine to make up the cost for other cities.
- more population, so you can have political advantage and force the UN to agree with you on everything.
- more (natural) resources, so you can have competitive edge on trade or making citizens happy. The Arabian oil is a prominent example. If only the Middle East is one country...
In the real world, this means that as powerful a small nation can be, it cannot become the next superpower without territory. Great leaders know this, and brings them to the next section...
Wars have great cost but magnificent benefits
Yap all you want about how bad wars are, but seeing the above benefits of larger territory, don't you wish that your country is a bit larger? Past, present, and future/candidate superpower civilizations all have a large area of territory at some point and lust for it: Greece, Roman Empire, Mongol Empire, China, Russia, United States, England, Japan... (not exhaustive and in no particular order)
Even so, a war puts all the nation towards military power building and neglects a lot of other things like culture building or research. Your opponent also suffers the same fate, but neutral parties don't; so expect your neutral rivals to be a bit ahead after a long war. But surely you have calculated everything before war and can catch up with them with all those war benefits, right?
Oh, and politically, other nations can curse all they want for the war you initiate, but seeing piles of resources you acquire and how you crush their best friend usually settle the issue.
A holy city in a right place means war
I presume you all know about Jerusalem---a holy city sought by everybody until today. It has all these properties:
- It is a holy city of multiple religions, so a multitude of pilgrims and tourists are supposed to come every day, boosting commerce.
- It is located on a fertile land rich with natural resources.
- It is located near disputed border of nations, so it is prone to attempts of takeover.
In the game, each of these points attracts AIs to try to take over a city. As all points are present in Jerusalem, it is no wonder what happens today.
Technology works well with politics
Give backward nations access to your technology and it may become your best friend. Trade technologies with friend nations so that you can have guns but your rivals have only swords. Then extort tribute or crush your rivals.
No nations are true friends though, so don't teach them how to make aircraft carriers if you don't want them to fight you back with your own weapons. But teach your allies to do that (and never let them to be bigger than you) and soon you can rule the world.