Inferno – “A fitting image for you” [Campaign 5, Mission 2]

Hello, I can't complete the quest. Eduardo attacks me at the beginning of the mission, and I can't defeat him. My army is too small to win, and I've restarted the mission three times, but I still can't win. He also attacks me when I'm playing the first mission as Sandor; he attacks me immediately after I capture the castle. Please help me figure out how to defeat him!