The only way to get more heroes to join your armies is through the Recruit Hero Action. The Recruit Hero Action takes 1 Hero Action and is performed in the following way:
To recruit another hero, roll 1 confessor die. If you roll 1 of the 2 shields, you have successfully recruited a hero. If you roll 1 of the 3 pikes or a cross, you are unsuccessful. *Heroes seeking to recruit from a territory with a castle receive a bonus. If your hero is on a territory with a castle, you gain the cross symbol in addition to the shield symbols. This means your chances to successfully recruit go up from 33% up to 50%. In this case, you can roll either a shield or a cross to successfully recruit.
Notice the Army Mat of Ferdinand I above. His default ability as a commander is the Recruit 1 ability (see the shield with a “1” on it at the left). This means that he is able to perform the recruit hero action from the beginning of the game. You will also notice that he can gain the Recruit 2 ability (the shield with the “2” on it) if he stays alive and continues to advance in hero abilities. This would give Ferdinand an extra die to roll when trying to recruit a hero.
When you successfully recruit a hero, take the top hero off the stack of your unused heroes and place it in front of you. Put a hero marker down on your card and place your hero anywhere on the game board where you have a single soldier holding down a territory. You may also place a prince or general on a territory where you have a lone confessor. You can also place a confessor on a territory where there is a prince or general because a confessor does not have an army. However, you may not place any hero on a territory that has not been occupied by your forces. You will also not be able to place a confessor on a territory where there is already another confessor nor will you be able to place any other hero with an army (commander, prince, general) on any territory with an occupying army (commander, prince, general). Obviously, you may not even perform the Recruit Hero Action if you do not have territories that meet the criteria above. It would be just a wasted action. If you have taken a chance at getting a confessor (which you could have placed), but instead got a general (which cannot be placed), then you have wasted the action. It is lost. Reshuffle unused heroes, place them face down, and try again later. When you successfully recruit a new hero, the hero is in play immediately. You do not have to wait till the next turn to conduct their Hero Actions.