Æthelstan or Athelstan (Old English: Æþelstan, Æðelstān; c. 893/895 – 27 October 939) was the King of England from 924 or 925 to 939. He was the son of King Edward the Elder and his first wife, Ecgwynn. Æthelstan's success in securing the submission of Constantine II, King of Scots, at the Treaty of Eamont Bridge in 927 allowed him to claim the title of 'king of the English', and even "by wishful extension" 'king of Britain'. Victory over Scottish and Viking forces at the Battle of Brunanburh in 937 confirmed his prestige. His reign has been overlooked, overshadowed by the achievements of his grandfather, Alfred the Great, but he is now regarded as one of the greatest kings of the West Saxon dynasty. Æthelstan was the first king of a unified England from 927, and his reign was of fundamental importance to political developments in the 10th century.

The materials for a life of Æthelstan are very limited, and the first biography, by Sarah Foot, was only published in 2011. The Anglo-Saxon Chronicle in this period is principally devoted to military events, and as Æthelstan's achievements were mainly in the reconstruction of the church and government, it is largely silent during his reign apart from recounting his military triumphs. The main source for his life is the twelfth century chronicle of William of Malmesbury, but historians are cautious about accepting his testimony, much of which cannot be verified from other sources. David Dumville goes so far as to dismiss William's account entirely, regarding him as a "treacherous witness" whose account is unfortunately influential. However, Sarah Foot is inclined to accept Michael Wood's argument that William's chronicle draws on a lost life of Æthelstan, while cautioning that we have no means of discovering how far William 'improved' on the original.

England ⁱ/ˈɪŋɡlənd/ is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, while the North Sea to the east and the English Channel to the south separate it from continental Europe. Most of England comprises the central and southern part of the island of Great Britain in the North Atlantic. The country also includes over 100 smaller islands such as the Isles of Scilly and the Isle of Wight.

The area now called England was first inhabited by modern humans during the Upper Palaeolithic period, but it takes its name from the Angles, one of the Germanic tribes who settled during the 5th and 6th centuries. England became a unified state in AD 927, and since the Age of Discovery, which began during the 15th century, has had a significant cultural and legal impact on the wider world. The English language, the Anglican Church, and English law—the basis for the common law legal systems of many other countries around the world—developed in England, and the country's parliamentary system of government has been widely adopted by other nations. The Industrial Revolution began in 18th-century England, transforming its society into the world's first industrialised nation. England's Royal Society laid the foundations of modern experimental science.