From "Debrett's Kings and Queens of Britain" by David Williamson, ISBN 0-86350-101-X, p. 21:
After his mother died, his sorrowing father, Ethelwulf, resigned his kingdom to his son Ethelbald and went on a pilgrimage to Rome, taking with him his youngest son Alfred, a boy of some 8 years, who had already been to Rome 3 years before. They were well received by Pope Leo IV who administered the rite of confirmation to Alfred, an act mistakenly taken by Asser, King Alfred's biographer, to be a consecration to future kingship, which was hardly foreseeable as Alfred had three elder brothers living. Ethelwulf and Alfred stayed in Rome for a year and on the return journey stopped at the court of Charles the Bald, King of the Franks and Charlemagne's grandson.

From "Debrett's Kings and Queens of Britain" by David Williamson, ISBN 0-86350-101-X, p. 22-4:
Ethelwulf's 3d son succeeded his brother Ethelbert and spent his whole reign fighting the Danish invaders, in which he was ably assisted by his youngest brother, Alfred. Some time after Easter (15 Apr) 871, Ethelred was wounded at Merton and died of his injuries. Ethelred was married and had two sons, Ethelhelm and Ethelwold, but they were considered too young to reign and he was succeeded by his brother Alfred. Alfred is the only English king (Canute was Danish) to have been designated 'the Great' and also the first to have a contemporary biographer in the person of Asser, the Welsh-born Bishop of Sherborne. Alfred was born at the royal manor of Wantage in Berkshire (now re-located in Oxfordshire) in 849, according to Asser, but elsewhere he is stated to have been 23 years old at his accession, implying a date of 847 or 848, which seems more likely in view of his early prowess against the Danes.
Alfred's great love of learning, which was manifested in later life, was inculcated by his mother who showed her sons a beautifully illuminated book of poetry and promised to give it to the first one to learn to read it. Alfred was the winner. While still in his teens, he became the right hand of his brother King Ethelred and proved himself an able commander in the struggle against the Vikings. In 868 he married Ealhswith, the daughter of Ethelred Mucil, Ealdorman of the Gaini (a Mercian tribal group), and Eadburh (Eadburga) a descendant of the Royal House of Mercia. She bore him a large family, of whom two sons and three daughters survived infancy.
When Alfred succeeded his brother Ethelwulf as king in Apr 871, the country was largely overrun by Danish invaders. A month after his accession he won a victory at Wilton and followed it up with a number of other successful skirmishes in the south of England, but within two years the Danes had most of Mercia and Northumbria in their grasp. Alfred's brother-in-law, King Burhed of Mercia, was driven out and went to Rome, where he died. After winning a sea battle in 875, Alfred concluded an uneasy and short-lived peace treaty with the invaders in 876. Further incursions into Devon soon followed and the Danes took refuge in Exeter where more peace negotiations took place. They withdrew to Mercia in the autumn of 877.
Alfred retired with his army into the island of Athelney, an inaccessible marshy area of Somerset. To this period belongs the story of Alfred disguising himself as a wandering harper and entering the Danish camp to gain vital knowledge of the enemy. Also attributed to this time is the story of the King taking refuge in a swineherd's hut and being soundly berated by the swineherd's wife for burning the cakes she had set him to watch.
Alfred left Athelney in May 878 and led his army into Wiltshire, being joined by large contingents from Somerset, Wiltshire and Hampshire. He met the Danes at Ethandune (Edington) and gained a resounding victory, driving the enemy back into their stronghold at Chippenham. The peace terms were settled a few weeks later, the Danes agreeing to withdraw from Wessex and return into East Anglia, Mercia and Northumbria, which were ceded to them and became known as the Danelaw. Their leader, Guthrum, accepted Christianity and Alfred stood sponsor at his baptism, giving him the name of Athelstan.
Over the next few years Alfred consolidated his kingdom, reorganizing the army, strengthening the defenses, encouraging learning and religion and codifying laws. Alfred was a polymath and could turn his hand to most things, including the translation of classical texts and the invention of a candle-clock. For the better government of his realm he called together a great council of bishops, ealdormen and thanes to meet twice a year, the first embryo parliament.
Asser tells us that Alfred was afflicted with a mysterious illness which attacked him periodically causing great pain. This might be porphyria. Alfred died on 26 Oct 899 and was buried at Winchester. His wife Ealhswith survived until 5 Dec 902.

From Anglo Saxon England, by Sir Frank Stenton, ISBN 0-19-282237-3, page 13:
The strongest evidence for the northern origin of the Angles is the narrative of a voyage from Oslo fiord to Slesvig which King Alfred prefixed to his translation of the history of Orosius. After the narrator has described how Jutland and many islands lay on the starboard for the last two days of the voyage, Alfred, interpolates the remark that the Angles dwelt in those islands before they came hither to this land. On a point like this, Alfred, who was saturated in English traditions, is an authority of the first order.