The fictional characters in The Circle of Ceridwen Trilogy play upon a stage of actual historical events.  I have used as my framework the Anglo-Saxon Chronicle, a series of histories that King Ælfred (b.849-d.899) commissioned during his lifetime.  The Chronicles were written in Old English save for Manuscript F, written in Old English and Latin.  Unnamed scribes in various religious foundations assembled the Chronicles*; the dates they cover range from Year One to 1154, the final year covered in the version known as the Laud Chronicle.  The Anglo-Saxon Chronicle itself makes fascinating reading and is a primary source for what we know of the period.

A few of the more important dates incorporated in The Circle of Ceridwen Trilogy include:

871: King Æthelred of Wessex and his young brother Ælfred fight against the Danes at Basingas (modern day Basing); the Danes take the victory.  Two months later Æthelred and Ælfred again face the Danes at Meredune (Marton), and after fierce fighting and great losses on both sides the Danes win.  Æthelred soon dies (possibly from wounds suffered at Meredune) and his twenty-three year old brother Ælfred is named king.

874: King Burgred of Mercia driven overseas by Danes after ruling twenty-two years

875: King Ælfred of Wessex launches naval foray in the Channel, fighting against seven Danish ships and capturing one

877: After a battle and seige at Exanceaster (Exeter) the Danish leader Guthrum makes peace with Ælfred, and Guthrum and his picked men swear oaths of peace upon an huge silver (sometimes recorded as gold) armring, held sacred to them.  One hundred and twenty Danish ships lost in bad weather at Swanawic (Swanage)

878: At Twelfthnight, while Ælfred was keeping Yule at his estate at Cippenham (Chippenham), Danes launch a surprise attack, sweeping over Wessex and driving the king into hiding, and many overseas.  Seven weeks after Easter Ælfred rallies enough troops to challenge the invaders.  In open battle the Danes are routed and take refuge at Cippenham where after a siege they surrender.  Guthrum and his thirty closest men swear to leave Wessex and to accept baptism.  The resulting treaty is known as the Peace of Wedmor (Wedmore), where the conclusion of the baptism festivities were held.  The Anglo-Saxon Chronicle records: "Guthrum...was twelve days with the king, who greatly honoured him and his companions with riches."
 

*There are seven extant versions of the Chronicle, and a few fragments beside.  The most important are known today as Manuscript A (The Parker Chronicle) Corpus Christi College, Cambridge, MS. 173; Manuscripts B and C (The Abingdon Chronicles) British Museum, Cotton MS. Tiberius A vi and Tiberius B i, respectively; Manuscript D (The Worcester Chronicle) British Museum, Cotton MS. Tiberius B iv; Manuscript E (The Laud (Peterborough) Chronicle) Bodleian MS. Laud 636; and Manuscript F (The Bilingual Canterbury Epitome) British Museum, Cotton MS. Domitian A viii.