Following their victory, the Neustrians joined with Radbod, King of the Frisians and invaded Austrasia, aiming towards the Meuse river to take the heartland of the factions support. It is at this moment that Charles Martel is first mentioned in historical records, which note him surviving imprisonment by his step-mother Plectrude. Charles managed to escape and mustered an Austrasian army to face the encroaching Radbod and the Neustrians. In 716, Charles finally met the Frisians as they approached and, although the "AMP" attempts equalize the losses, it is confirmed from the descriptions in the "LHF" and the "Continuations" that Charles was defeated with heavy losses. Chilperic and Raganfred, and according to the "Continuations," Radbod then travelled from Neustria through the forest of the Ardennes and raided around the river Rhine and Cologne, taking treasure from Plectrude and her supporters. As they returned, Charles ambushed the returning party at the Battle of Amblève and was victorious; inflicting heavy losses on the Neustrain invaders.