As fortresses are created out of 5 castles, you will also need five times the regular amount of silver in order to conquer another fortress. That also means that if you should conquer a fortress and meanwhile launch an silver carrying attack on a second fortress, you will need 25,000 silver more on the second fortress than you have needed for the first one. In general you can use the following values in order to get the right numbers: A new fortress will set the required silver for the next castle to 5000 and for the next fortress to 25,000.
For Instance:
- Should you need 381,000 silver for another castle to be taken over, you will need 1,905,000 for a fortress
- Should you be conquering a castle then the same costs would be raised to 382,000 silver and 1,910,000 respectively
- Should you instead be conquering a fortress, then the required silver amount for the next fortress will be at 1,930,000 silver
Basically, the following values can be used as a guideline:
A new castle means that the next castle will cost 1,000 silver, the next fortress will cost 5,000 silver, and the next city will cost 25,000 silver more.
A new fortress implies that the next castle will cost 5,000 silver, the next fortress will cost 25,000 silver, and the next city will cost 125,000 silver more.
A new city means that the next castle will cost 25,000 silver, the next fortress will cost 125,000 silver, and the next city will cost 625,000 silver more.