as charles's archchancellor for lotharingia from january 916, ruotger had a large role in securing the king's authority in lotharingia, culminating in the treaty of bonn in 921, in which the east frankish king, henry the fowler, recognised lotharingian as belonging to west francia. ruotger also became involved in a conflict with giselbert, duke of lotharingia, over the basilica of saint servatius in maastricht.