The people of Jászberény (YOSS-beh-ray-nyuh) long displayed the horn used to kill a ruler of this name after a defeated chieftain legendarily pretended to blow it, then struck that ruler. The grandparents of a ruler with this name established an imperially patronized abbey whose history was written by its resident playwright, Hrosvitha of Gandersheim. Heribert Illig proposed that a Byzantine Emperor, a Pope, and a ruler with this name invented 300 years of history according to his (*) phantom (10[1])time (10[1])hypothesis. Liufeld revolted against his father of this name, who answered Pope John XII’s call to defend Rome against Berengar II. With Conrad the Red, a ruler of this name ended Magyar expansion at the Battle of Lechfeld. For 10 points, give this name held by a succession of 10th-century Saxon Holy Roman Emperors. ■END■