Asser is remembered as the author of a Latin biography of King Alfred ('the Great') of Wessex, written during the king's lifetime. He was a monk at St.David's, Pembrokeshire, and, according to his 'Life of King Alfred', he was one of a number of scholars who Alfred invited to his court "to aid him in his strivings after wisdom". In about 884 Asser arrived:
"... in the country of the Saxons, who live on the right hand, which in Saxon is called Sussex, under the guidance of some of that nation; and there I first saw him in the royal vill, which is called Dene. He received me with kindness, and among other familiar conversation, he asked me eagerly to devote myself to his service and become his friend, to leave every thing which I possessed on the left, or western bank of the Severn, and he promised he would give more than an equivalent for it in his own dominions. I replied that I could not incautiously and rashly promise such things; for it seemed to me unjust, that I should leave those sacred places in which I had been bred, educated, and crowned, and at last ordained, for the sake of any earthly honour and power, unless by compulsion. Upon this, he said, "If you cannot accede to this, at least, let me have your service in part: spend six months of the year with me here, and the other six in Britain." To this, I replied, "I could not even promise that easily or hastily without the advice of my friends." At length, however, when I perceived that he was anxious for my services, though I knew not why, I promised him that, if my life was spared, I would return to him after six months, with such a reply as should be agreeable to him as well as advantageous to me and mine. With this answer he was satisfied, and when I had given him a pledge to return at the appointed time, on the fourth day we left him and returned on horseback towards our own country.

After our departure, a violent fever seized me in the city of Winchester, where I lay for twelve months and one week, night and day, without hope of recovery. At the appointed time, therefore, I could not fulfil my promise of visiting him, and he sent messengers to hasten my journey, and to inquire the cause of my delay. As I was unable to ride to him, I sent a second messenger to tell him the cause of my delay, and assure him that, if I recovered from my infirmity, I would fulfil what I had promised. My complaint left me, and by the advice and consent of all my friends, for the benefit of that holy place, and of all who dwelt therein, I did as I had promised to the king, and devoted myself to his service, on the condition that I should remain with him six months in every year, either continuously, if I could spend six months with him at once, or alternately, three months in Britain and three in Saxony. For my friends hoped that they should sustain less tribulation and harm from king Hemeid, who often plundered that monastery and the parish of St.Deguus, [St.David] and sometimes expelled the prelates, as they expelled archbishop [of St.David's] Novis, my relation, and myself; if in any manner I could secure the notice and friendship of the king...

... When therefore I had come into his presence at the royal vill, called Leonaford, I was honourably received by him, and remained that time with him at his court eight months; during which I read to him whatever books he liked, and such as he had at hand; for this is his most usual custom, both night and day, amid his many other occupations of mind and body, either himself to read books, or to listen whilst others read them. And when I frequently asked his leave to depart, and could in no way obtain it, at length when I had made up my mind by all means to demand it, he called me to him at twilight, on Christmas eve, and gave me two letters, in which was a long list of all the things which were in two monasteries, called in Saxon, Ambresbury [Amesbury] and Banwell; and on that same day he delivered to me those two monasteries with all the things that were in them, and a silken pall of great value, and a lead for a strong man, of incense, adding these words, that he did not give me these trifling presents, because he was unwilling hereafter to give me greater; for in the course of time he unexpectedly gave me Exeter, with all the diocese which belonged to him in Saxony and in Cornwall, besides gifts every day, without number, in every kind of worldly wealth, which it would be too long to enumerate here, lest they should make my reader tired. But let no one suppose that I have mentioned these presents in this place for the sake of glory or flattery, or to obtain greater honour. I call God to witness, that I have not done so; but that I might certify to those who are ignorant, how profuse he is in giving, he then at once gave me permission to ride to those two rich monasteries and afterwards to return to my own country."
At the time of his death (in 909) Asser was bishop of Sherborne. The 'Life of King Alfred' begins, not surprisingly, with Alfred's birth, which Asser places in 849. Much of the material is obviously derived from the 'Anglo-Saxon Chronicle', and the last quoted date is 887 (but a passing mention of Alfred's forty-fifth year appears to indicate that the 'Life' was written in 893). The sole surviving manuscript was destroyed in the infamous fire which ravaged the library of Sir Robert Bruce Cotton (1571-1631), on Saturday 23rd October 1731. An edition of the text, with additions and alterations, had been published by Archbishop Matthew Parker in 1574. A reprint of Parker's edition, made by antiquary and historian William Camden in 1602, included further deviations from the original. Another edition, published by Oxford scholar Francis Wise in 1722 (only nine years before the manuscript was destroyed), failed to expunge the interpolations and errors the work had acquired. Although not widely accepted, there have, since the 19th century, been suggestions that Asser is not the author of the 'Life'. The absence of any clues the Cotton manuscript might have provided, would seem to preclude the possibility of making a definitive judgement concerning the work's provenance.

'Life of King Alfred' translated by Dr. J.A. Giles