DYNASTY WARRIORS 9 Empires

You can get this achievement by bringing new officers into your kingdom, go on a stroll and interact with unaffiliated officers and then recruit them when the chance is higher than 60% which usually succeeds.

A ruler can also use the 'appoint' command to appoint officers to a role which contributes towards this achievement and using 'scout' should also work (although I can't verify as I mostly use the stroll method).