Recruitment

To expand your army, you can use the recruitment screen to hire new units. Hiring units requires gold and supply. If you want to hire while in a region, you also need a captured settlement from where units can be deployed. You can also hire mercenaries who are cheaper and do not require supply, but only join temporarily.

Units that suffered casualties are restored to full health at the conclusion of a battle, but as new recruits join their ranks, their experience level drops. You can spend gold to fill their ranks with experienced recruits instead, mitigating the experience loss.

Recovery
Units can rest to recover their wounds and heal wounded individuals so they become active members again. Whenever squad members are wounded, there is a chance for them to be killed, resulting in a black segment in that unit's health bar. Killed unit members cannot be recovered by resting but will be refilled with fresh recruits after winning the region. Replacing dead unit members lowers a unit’s experience, often resulting in a loss of levels.