NintendoTogepi
Noble Pacifist
I've heard so many different eras, from trying to do a Axe rush or teching to Mechanized Infantry and wiping everything out from there.
What is the best time?
What is the best time?
When you can afford it.
Rush is good if (and only if) your expected win/loss ratio is good.
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So, any age is good for warring but don't forget to perform cost & benefits analysis.
I think that early game rush is super-beneficial. Granted, there's a lot of good wonders to build then, but taking control of something early, you can go on and improve the cities to your liking and have them grow to be powerhouse places in your own empire. A late game city spends so much time climbing out of the hole from when you conquered it.
Sometimes it pays to be a little patient. If my neighbour has founded a religion and has Oracle or Stonehenge as well I'll wait for him to build me the Shrine before taking his holy city. That effectively gives me an extra GP.
I more-or-less agree with what you're saying, because war should be worth more than it costs.
But it sounds like you are only considering the immediate costs/benefits of destroying an enemy or capturing his city. There are ample intangible future benefits that can make even a BAD short-term decision a GREAT long-term decision. .