During his invasion of Scotland, Siward, Earl of Northumbria, defeated Macbeth, King of Scotland, in an engagement north of the Firth of Forth.

Siward or Sigurd was an important earl of 11th-century northern England. The Old Norse nickname Digri and its Latin translation Grossus are given to him by near-contemporary texts. He emerged as a regional strongman in England during the reign of Cnut. Cnut was a Scandinavian ruler who conquered most of England in the 1010s, and Siward was one of many Scandinavians who came to England in the aftermath, rising to become sub-ruler of most of northern England. From 1033 at the latest, he was in control of southern Northumbria, present-day Yorkshire, governing as earl on Cnut's behalf.

Macbethad mac Findláech, nicknamed the Red King, was King of Scotland from 1040 until his death in 1057. He ruled during the period of Scottish history known as the Kingdom of Alba.

The Firth of Forth is a firth in Scotland, an inlet of the North Sea that separates Fife to its north and Lothian to its south. Farther inland, it becomes the estuary of the River Forth and several other rivers.