As you progress through the different stages of the game, completing quests becomes more challenging. In some cases, you will need to equip a specific General to earn influence and advance.

You can identify the required General by looking at the picture displayed on the left side of the quest. To equip them, click on the large portrait of your currently selected General in the top-right corner of the screen. From there, select the required General from your list.

Make sure to check which General is needed before attempting a quest to ensure you can earn the required influence.