Norman Conquest Encyclopedia

River Ouse

In the first week of September, 1066, Harald Hardrada and Tostig Godwinsson raided the coast of Northumbria, now Yorkshire, from the River Tyne to the Humber, and then entered the Humber, sailed up the River Ouse and encamped at Riccall, ten miles (16km) south of York. From there Hardrada went on foot and was met by Edwin of Mercia and Morcar of Northumbria at Gate Fulford where a hard battle, the first of two in the space of five days, was fought.

You can find out more about the Norse invasion in the following Osprey books:
Campaign 13 Hastings 1066 pages 43-44
Elite 3 The Vikings page 26
Landmarks in History The Norman Conquest pages 12-13.