A successful siege will bag you the most influence, but you can still earn a lot from basic field battles if the opponent is powerful enough. The most influence comes from participating in battles alongside other powerful nobles, against powerful nobles of enemy factions. The more the odds are against you and your allies in any given battle, the more influence you will gain if you win the battle. In terms of the most basic method of accruing influence, you will gain it after winning any battle that you’re involved with. When you first join a kingdom, your influence will be zero or close to it. Without influence, you will be unable take part in any aspect of political decisions, and you will be vulnerable to sabotage from other clan leaders. The amount of influence that you have will determine whether or not the nobility within a kingdom will agree with your decisions, or even listen to a proposal in the first place. The influence system in Mount & Blade II: Bannerlord is simple, but highly important once you join a kingdom as a mercenary or vassal.
