Fullmetal Alchemist: Brotherhood - episode 55 - 01 May, 2010

The Armstrong siblings have trouble fighting off both Sloth and the mannequin soldiers, until Izumi and Sig arrive. Through the combined efforts of Armstrong and Sig, they manage to deal enough damage to Sloth to finally kill him, before turning their attention to the mannequin soldiers. Meanwhile, Hohenheim fights with Father underground. In the midst of the battle, Father is unable to take the philosopher's stone from within Hohenheim, since the latter feels that he is missing something. With the majority of the Central Command Headquarters captured, the Briggs Fortress soldiers start to celebrate until Bradley, still alive, approaches the headquarters, promising to reclaim it. (Source: Wikipedia)