Battle of Two Rivers The Battle of Two Rivers was fought between the Picts and Northumbrians in the year 671 . The exact battle site is unknown . It marked the end of the Pictish rebellion early in the reign of Ecgfrith , with a decisive victory to the Northumbrians . Attestation of the battle is limited to the account in Stephen of Ripon ' s " Vita Sancti Wilfrithi " . Background . During the 7th century , the Northumbrians gradually extended their territory to the north . The Annals of Tigernach record a siege of " Etain " in 638 , which has been interpreted as Northumbria ' s conquest of Din Eidyn ( Edinburgh ) during the reign of Oswald , marking the annexation of Gododdin territories to the south of the River Forth . To the north of the Forth , the Pictish nations consisted at this time of the kingdom of Fortriu to the north of the Mounth , and a " Southern Pictish Zone " , to the south , stretching as far as the Forth . Evidence from the 8th century Anglo - Saxon historian , Bede points to the Picts also being subjugated by the Northumbrians during Oswald ' s reign , and that this subjugation continued into the reign of his successor , Oswiu . Ecgfrith succeeded Oswiu as king of Northumbria in 670 . Ecgfrith ' s kingdom was said to have been ' weak ' on his ascent to the throne . In 671 , word reached Ecgfrith that the Picts , under the command of the Verturian king , Drest mac Donuel , were preparing to rebel and overthrow the Northumbrian hegemony . Account of battle . The record and description of the battle is limited entirely to Stephen of Ripon ' s account in his " Vita Sancti Wilfrithi " . According to this account , Ecgfrith became aware of the Picts plans to overthrow the Northumbrian suzerainty and he hastily assembled an invasion force of horsemen . He headed north , aided by his subking Beornhæth , who historian James Fraser suggests may have ruled the southern Pictish kingdom of Niuduera , identified as being located in present day Fife . The battle location is not recorded , but Fraser tentatively suggests that the battle may have occurred in the vicinity of Moncreiffe Island , near Perth . As recorded in " Vita Sancti Wilfrithi " , Ecgfrith ' s cavalry was ambushed by a concealed and much larger Pictish army . Nevertheless , the Northumbrians prevailed , with Pictish casualties being of sufficient number to ' fill two rivers ' , allowing the Northumbrian cavalry to pursue Pictish survivors without getting their feet wet . As a work of hagiography , " Vita Sancti Wilfrithi " is not an ideal historical source and it has been suggested that its partisan treatment of Northumbrian history inspired Bede ' s " Historia Ecclesiastica " . Various details of Stephen ' s account of the battle are likely to have been exaggerated , overstating the extent of Ecgfrith ' s victory . Aftermath . Stephen records that , following the battle , the Picts were reduced to slavery and subject to the yoke of captivity for the next 14 years . The Irish annals of Ulster and Tigernach record of a ' Drost ' being expelled from kingship in 671 . It is generally presumed that this was the Pictish king , Drest , and that he was deposed and replaced by Bridei mac Bili as a direct result of the failure of the Pictish rebellion . Bridei was later to defeat and kill Ecgfrith in the Battle of Dun Nechtain in 685 .