During his reign Athelstan became the first English king who ruled over the whole of the land that is known today as England. He achieved this through a combination of diplomacy and military strength. On his accession the kingdom of the Northumbrians was ruled by the Danish king, Sihtric. In 926 Æthelstan and Sihtric met at Tamworth, the capital of Mercia, where they made an alliance sealed by Sihtric's marriage to a sister of Athelstan.  Sihtric died in 927 and Athelstan seized control of Northumbria. To consolidate his position Athelstan summoned Welsh princes and Constantine king of the Scots to Eamont, near Penrith on 12 July 927 and they acknowledged his position as the most senior ruler in the island of Britain. Peace with Constantine of Scotland broke down in 934 and Athelstan marched north to assert his power.

Athelstan’s authority was challenged again in 937 by a hostile alliance led by Constantine, Olaf or Anlaf Guthfrithson, a Danish ruler based in Dublin, and Owain, king of Strathclyde. Athelstan engaged in battle with his enemies at a place called ‘Brunanburh’. It is entirely possible that men from Malmesbury were present at this historic encounter. At the Battle of Brunanburh Athelstan was triumphant, inflicting heavy losses on his enemies.

The precise location of the site of the Battle of Brunanburh is disputed but was probably somewhere in northern England. In recent years Michael Wood has argued for a location in the area to the south of York while others, including Michael Livingston, have proposed a site on the Wirral peninsula near Liverpool. The Wirral town of Bromborough has a name that is very similar to that of ‘Brunanburh’ and may be close to the battlefield.