Alfred the Great (ca. 849-899) - Alfred was the grandson of King Egbert and the only Anglo-Saxon monarch bestowed with the epithet of "Great" (Canute the Great ruled England, but was Danish).  He earned it largely through his vigorous defense of the British Isles against the Viking invasions.  This was before the island was united into a single country of England, and his kingdom was Wessex in the southwest.  He was the youngest of five sons of King Æthelwulf.  The oldest son never ruled (except as sub-king of Kent) as he died before Æthelwulf.  But his three other brothers all served as king for a brief period before Alfred himself inherited the throne.  And all of Æthelwulf's sons were involved to some extent in defending England against the Viking invasions.  Northern Europe had become a battleground for the Norsemen, and the island was eyed as fertile territory.  So thousands of them sailed west and attempted to displace the Saxons, who themselves had displaced the indigenous Britons centuries earlier (see Anglo-Saxon invasions).  Alfred enters the pages of history in 866 (in the Anglo-Saxon Chronicle), a year after his brother Æthelred became king.  Alfred was prince of Wessex at the time and a major contributor in the cause of driving the Vikings from their land.  He and Æthelred fought side by side when they won the crucial Battle of Ashdown in January of 871.  However, the Saxon's lost to the Danes in March of that year at Meretun and Æthelred died a month later (whether he died in battle or from wounds suffered at Meretun is unknown).  Despite the fact that Æthelred had two sons (both underage), it was agreed at the Witan of Swinbeorg that Alfred would succeed him if he died before his sons were old enough.  And so Alfred became King of Wessex at the age of either 21 or 22, in the midst of a Viking invasion.

His enemies were the brothers Ragnarson; Ivar (the Boneless), Ubba and Halfdan.  They were sons of the legendary Viking, Ragnar Lodbrok.  The Anglo-Saxon Chronicle refers to their army as the "Great Heathen Army".  Alfred had to deal with the Danes his entire reign, and at one point Wessex was the only Saxon kingdom left to oppose them.  Even it was almost lost, but Alfred won a decisive victory at the Battle of Edington and Wessex was preserved.  It should be noted that Alfred did not completely defeat the Viking invaders, but rather reached a state of "detente" with them.  They were too numerous to expel from the island, and as a devout Christian, he believed it was wrong to slaughter them outright.  So he agreed to let them stay provided they converted to Christianity and learned to speak English, both of which they did.  Although he did not achieve total victory over the Vikings, it is largely because of Alfred that the island is called England today rather than "Daneland".  Besides the Anglo-Saxon Chronicle (which was compiled during Alfred's reign), the primary source for Alfred's life comes from the Welsh scholar, Bishop Asser