I just found out, that I cannot have more that 300 ongoing millitary missions going at the same time....Since when is my question?! Because I check the forum regularly, and did saw anywhere anything about setting a bar limit for that....!!!

This is one unadvertised limitation. Apperently it is a limitation of Adobe. I found it by mistake while taking part in the weekly siege contest. The 300 operations include any combination of raids and sieges. One must complete before the next one starts. I could find no documentation of this limit either.