But it seems random. My noble (with 100+) men received the message the first two times he did takeover actions, but not the third. And he actually had more men the third time, as some had healed from previous combat.
There is some randomness involved in the TO mechanics. If (arbitrary numbers) the reporting threshold is 100 and your effect is # of men +/-20 then you can well go over the threshold with 90 men, but miss it with 110.
