Idalberto discovers his mother arming herself for battle, ready to fight alongside her troops. He begs her not to, but she scornfully refuses to listen to her son express such cowardice. Clorimundo enters with the news that the battle is over and Lotario has won. The enraged Matilde accuses her son of causing this defeat and orders Adelaide brought to her so that she can kill her with her own hands but is told that Adelaide has already been released. Idalberto suggests to his mother that she kill him instead which strikes Matilde as a good idea, but she cannot quite bring herself to do it. The victorious Lotario enters and orders Matilde arrested whereupon she tries to commit suicide but is prevented.