 Against his father's policy, Berchar did not maintain peace and incited Pippin into violence.In 687, Pippin rallied an Austrasian army and led an assault on Neustria, facing Theuderic III and the Neustrian mayor, now Berchar, in combat.They met at the Battle of Tertry, where the "AMP" records that Pippin, after offering peace which was rejected by Theuderic at Berchar's behest, crossed the river Omignon at the break of dawn and attacked the Neustrians who believed the battle won when they saw Pippin's camp abandoned.