Before you can unlock your retinue in Manor Lords, you need to build your manor. You can do this by reaching the Small Village Level with your settlement and having the appropriate materials available. You will need 5 timber, 20 planks, and 15 stone.

When you construct your manor, the retinue will appear. It will only have five soldiers at the ready with a maximum of twelve. Even with their small numbers, they can still make a big difference in any battle. If they die or you simply wish to fill empty positions, you can hire new members of your retinue.