The first king of unified England was Æthelstan, who reigned from 924 to 939. He was instrumental in consolidating various Anglo-Saxon kingdoms, having successfully united Wessex, Mercia, and other regions under his rule. Æthelstan's reign is often regarded as the birth of England as a united entity, establishing its capital at Winchester and promoting a sense of national identity. He implemented legal reforms and military campaigns to secure his realm against Viking incursions, paving the way for a more centralized governance structure. His influence on English history is significant, as he helped lay the foundations for a cohesive state.