Mount and Blade II: Bannerlord places you at the head of a steadily growing clan that you regularly manage and maintain. An essential feature as a clan leader is to ensure those under you have a critical role to play, and a great way you can help spread your name and extend your resources is to create a party within your clan.
To create a new party, you need to open up the clan screen. Go to the parties tab in the menu, and underneath your main character, you should have the option to create a new party, if your clan level is at least 2. You also need a companion who is up to the task. You should see any available companions under your employment who are available to lead that party.
When you choose to have them lead a new party, you go to a new menu where you can choose to give them any of your main character’s primary forces. You can transfer over as many troops as you feel they need, up to a certain amount. Companions have a maximum party size, just like your main character. When you finish, you can choose done in the middle of the menu.
The party will now appear as a moving force on the main screen, and you can see them wander around the map. They will have a green name and number while wandering around, and they hold your clan’s banner as a sigil. You can keep track of that new party by returning to the clan page to reviewing their progress and viewing their last location. The party will wander around the game on your behalf, freeing up your main character to obtain additional forces to their primary group. Once you level up your clan again, you can create new parties, adding more troops to operate under your banner.
You do need companions to lead these parties, so make sure to visit towns to recruit them so they can operate on your behalf. When you have a kingdom, you can keep track of these groups by clicking on the three flags in the lower right-hand section of your screen while viewing the large campaign map.