I would suggest that before you start comparing war in a game to real life that you study history a little. Many empires move in and take all the resources of small countries or territories.
Let me list a few empires and things in history that you can read up on to learn about with regards to forces and resources.
Vikings (first major raids were against abbeys and monistaries, killing everyone and taking everything)
Romans (expanded their empire by killing all opposition and taking all resources for their own empire, then enslaving any opposition that was still alive)
Great Britain (the British empire anyone?)
The Mongols (swept through Eurasia massacring whole cities and taking all resources then burning the cities to the ground)
The conquests of Alexander the Great (destroying enemy armies then claiming lands for his empire and funneling the resources where he wished.)
Also if you read about
the conquering of the new world by the Europeans:
The conquistadors enslaved thousands of natives, took all their gold and got fat on their food.
These are just a few examples, you can find even more on smaller levels. Such as little fiefdoms by dukes and lords in Europe.


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