 Robert II, Count of Flanders, allied with Bishop Manasses of Cambrai—a Frenchman supported by the Pope—against Walcher whom Henry had appointed to replace Manasses as bishop of Cambrai.Robert laid siege to Cambrai; Henry came to Walcher's rescue, forcing Robert to lift the siege in October 1102, but Robert resumed the war on Walcher soon after Henry left Cambrai.Henry held a general assembly in Mainz on 6 January 1103, and proclaimed the "Reichsfriede" (imperial peace), prohibiting feuds and other acts of violence, for the first time in the whole empire.