The throne of Wessex being in dispute, and Egbertís rivalís mind turning increasingly to thoughts of murder, Egbert deemed it prudent to leave the country. He spent thirteen years or so in Frankish dominions and then returned to England and finally ascended the throne of Wessex. For a while, Egbertís reign was peaceful, but eventually he started waging wars, the first being against Cornwall. The Celts of Cornwall were outnumbered and fell to Egbert.
Shortly after extending his dominions westward, the king of East Anglia asked Egbert to aid him in fighting the Mercians. Mercia at the time was the most powerful of the kingdoms of Britain, and held the advantage for a while, but eventually lost to the combined Wessex/East Anglia onslaught. Egbert, always one to strike while the iron was hot, rapidly took control of Surrey, Essex, and Sussex, and appointed his son Æthelwulf King of Kent.
Various wars followed, --though not with the kingdom of Northumbria. Egbert had planned to war with them, but the Northumbrians learned of his plans and immediately surrendered. Egbert now ruled a kingdom that extended to present day Scotland. Not content, however, Egbert warred against Wales and conquered much of it as well. (He had the sense not the fight the fierce Scots and Picts.)
A few years passed, and the Danish invasions began. Egbert marched against them and was trounced. Dismayed, he summoned a conference of prelates and nobles, but they seem to have reached no decision, and soon Egbert had to fight off a new invasion of Danes, this time winning hands down. He then took Chester, and further announced that all Welshmen and women had a choice: they could either leave England within six months, or they could leave this world. The Welsh believed that this and other anti-Welsh measures were more the doing of Queen Raedburh than King Egbert, as she was known to hate the Welsh, for unknown reasons.
Egbert died the following year and his son Æthelwulf succeeded to the throne.