Ahoy Captain! That's right. Their bonuses apply to their own units, even when the Units of other 2 Captains arrive on the Haven of the Captain who initiates Massed Attack. If ye have any other questions, please let me know.

if you're a brotherhood leader you can, the brotherhoodleader has an option to return all units from a presidio, but this only returns offensive units to their owners.

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Redbeard is correct and incorrect. By default it is only the BH leader who can authorize the return of OFFENSIVE units. However as you can see the third option available is to grant this ability to others. If doing so only rank I would suggest are Advisors.  Remember though to do this immediately after capping a presidio. Also you may need to do this periodically when players send daggers to presidios. And yes it happens. Unfortunately we don't have this function available to us for the bastions.

The only bonuses that apply to all are Knowledge but remember this only applies if they've been in the BH for 7 days. Also any boost from BH achievements are also granted to all players of your BH. Both are reasons to pay attention to your bastion and BH achievements

thanks icy, i forgot about the third option

*hugs*