In 716, Chilperic and Ragenfrid together led an army into Austrasia intent on seizing the Pippinid wealth at Cologne. The Neustrians allied with another invading force under Redbad, King of the Frisians and met Charles in battle near Cologne, which was still held by Plectrude. Charles had little time to gather men, or prepare, and the result was inevitable. The Frisians held off Charles, while the king and his mayor besieged Plectrude at Cologne, where she bought them off with a substantial portion of Pepin's treasure. After that they withdrew. The Battle of Cologne is the only defeat of Charles Martel's career.