Hire Population
The "Hire population" option allows you to get extra Population for all of your Castles. By using this option you increase the Population in all owned Castles at the moment by 20% for 7 days. This option costs 100 Coins and when it is used more than once before the 7-days period has expired, it doesn't increase the amount of Population but the duration of the option. Note that when the option expires your Castles might become overpopulated.
IMPORTANT:
This option doesn't increase any Population at Castles where the maximum level of the Dwellings is constructed.