The Northumbrian hegemony over Northern Britain, won by Ecgfrith's predecessors, had begun to disintegrate. Several of Northumbria's subject nations had rebelled in recent years, leading to a number of large-scale battles against the Picts, Mercians, and Irish, with varied success. Following sieges on neighbouring territories carried out by the Picts, Ecgfrith led his forces against them, despite advice to the contrary, in an effort to reassert his suzerainty over the Pictish nations.