Complex sentence: An unpaid position was created for Forssmann at the Berliner Charité Hospital, working under Ferdinand Sauerbruch, although once Sauerbruch saw his paper, he was dismissed for continuing without his approval.
Split into simpler sentences: An unpaid position was created for Forssmann at the Berliner Charité Hospital, working under Ferdinand Sauerbruch. Though, once Sauerbruch saw his paper, he was dismissed for continuing without his approval.