Sieges.

[Jon Agony]

Hello! A guy told me that if a castle have 9k troops you have to attack with atleast 3k troops and if the castle have 3k you have to attack with atleast 1k. Could not find anything about it in the rules so? 

[BASNAK]

Yes that is true. It is called the 1/3 rule.
Therefore you need 10k troops to attack 30k garrison.

[Erasmas]

This is correct. And it sux big time and should be fixed:

http://forum.meleegaming.com/strategus-general-discussion/why-the-current-battle-system-needs-a-fix-%28in-big-battles%29/