In 802 King Beorhtric died and Egbert returned to England and claimed the Wessex throne. Little is known of the early period of his reign but he must have spent time securing his authority and organising his kingdom and army. In 825 the Mercian King Beornwulf invaded Wessex but Egbert's preparations were tested and proved to be strong enough to defeat the invading Mercian army at the battle of Ellendun in Wiltshire. Egbert followed up this victory by sending his son Aethelwulf with an army into Kent, Surrey, Sussex and Essex each of which submitted.
In 829 Egbert invaded Mercia and defeated the Mercian King Wiglaf. He then went on into Northumbria where King Eanred submitted as well. For a short time Egbert was the bretwalda (the ruler of all of the Saxon states), but in 830 Wiglaf regained control of Mercia. The end of Egbert's reign was dominated by Danish invasions and in 836 the Vikings defeated Egbert at the battle of Carhampton. But Egbert came back in 837 and defeated the Vikings at the battle of Hingston Down.
Egbert died in the following year and was succeeded by his son Aethelwulf.