Hadrian II had earlier appointed Archbishop of Sirmium with jurisdiction over the realms ruled by Rastislav and Svatopluk. Early in 871 Carloman also imprisoned Svatopluk on unspecified charges of disloyalty, which may have been connected to the rebellion of Carloman's younger brothers, Louis the Younger and Charles the Bald. Believing that Svatopluk was dead, the Moravians selected another member of their ruling family named Slavomír and made him their ruler. Towards the Peace of Forchheim Carloman soon came to the conclusion that the accusations against Svatopluk were unfounded and released him from prison. In order to bind Svatopluk to his family, Carloman had Svatopluk stand as godfather to his illegitimate grandson. Thus this son of Carloman's son Arnulf received the Moravian name Zwentibold. Svatopluk also agreed to lead Carloman's armies against Slavomír and the rebellious Moravians. However, on his arrival at "Rastislav's old city", Svatopluk betrayed the Bavarians and conspired secretly with the rebels. Although he captured the fortress in accordance with Carloman's plan, once he was inside its walls he renounced his loyalty to Carloman, rallied a large Moravian force and launched a devastating surprise attack on the unsuspecting Bavarian army encamped outside. The Moravians took a great number of soldiers hostage, killed the rest and rid Moravia of the Frankish occupation. Carloman's governors, William and Engelschalk, were also both slain, and Svatopluk became the undisputed ruler of Great Moravia. In October 871 Louis the German sent Bavarian and Franconian troops against the Bohemians (Czechs). During the campaign the Franconians surprised a party of Moravians somewhere near the traps that guarded the narrow approaches to a Bohemian fort. The Moravians were returning to their homeland with the daughter of a Bohemian dux ("duke"), presumably to marry an unidentified Moravian magnate. Although the Moravians managed to reach the safety of the fort, they had to abandon 644 fully equipped horses in the narrows. The marriage of a Bohemian leader's daughter to a Moravian magnate implies that Svatopluk was planning to form an alliance with the Bohemians. Louis the German realized the grave threat posed by Svatopluk and assembled forces for a multipronged expedition with pincer movements advancing on Moravian territory from several directions in 872. One army was sent out "against the Moravian Slavs" from Regensburg (Germany) in May, but the Thuringian and Saxon soldiers fled in their first encounter with the enemy. The second army, composed of Franconians under