盎格魯-撒克遜人在爱尔兰和罗马派来的传教士的影响下,开始了基督教化的过程。但爱尔兰宗教仪式和大陆宗教仪式上的差别几乎导致不列颠基督教会的分裂,这一巨大的分歧在663年的Synod of Whitby(英语:惠特比宗教会议)上终于获得了解决。与此同时,修道院成为盎格魯-撒克遜时期的文化中心,那里以精美的手抄本而闻名。
604年,伯尔尼西亚的国王埃特尔弗里特(Æthelfrith,593年-616年在位)将两个小王国合并为诺森布里亚王国,并为统一后的王国增加了一部分苏格兰以及威尔士的领地。616年,埃特尔弗里特被流亡在外德拉的愛德温(Edwin)打败,并被取而代之。627年,愛德温接受了基督教,并在英格兰建立了诺森布里亚的霸权。可惜好景不常,632年,愛德温被威尔士格温内斯王国的国王卡德瓦尔隆(Cadwallon ap Cadfan)杀死,这个王国是和麥西亞国王彭达结盟以反对诺森布里亚的。经过一年的混乱后,诺森布里亚的王位由伯尔尼西亚的奥斯瓦尔德(Oswald)获得,他请来圣埃丹进行凯尔特基督教的传教工作。然而很快,642年,奥斯瓦尔德也被麥西亞的彭达杀死了。之后,奥西乌(Oswiu)(641年-670年在位)以及埃克格里菲斯(Ecgfrith)(670年-685年在位)先后继承王位。在这个时期中,诺森布里亚的国力逐渐衰微,麥西亞王国却国势蒸蒸日上。不过,奥西乌在宗教方面还是有所建树的,他在惠特比宗教会议上确立了罗马基督教会对凯尔特基督教会的领导权。
^Jones.The end of Roman Britain: Military Security. pp.164 - 168. The author discusses the failings of the Roman army in Britain and the reasons why they eventually left.
^Jones.The end of Roman Britain. p246. Roman Britain's death throes began on the last day of December 406 when Alans, Vandals, and Sueves crossed the Rhine and began the invasion of Gaul
^Dark. Britain and the End of the Roman Empire. p.29.Both Zosimus and Gildas refer to the 'Rescript of Honorius',a letter in which the Western Roman emperor told the British civitas to see to their own defence.
^Esmonde Cleary. The Ending of Roman Britain. pp.137 - 138. The author suggests that the 'Rescript of Honorius' may have been for a place in southern Italy rather than Britain and that the chronology is wrong
^ 5.05.1Morris. The Age of Arthur.pp.56 -62. Picts and Saxons.
^Myres. The English Settlements. p.14. Talking about Gildas references to the arrival of three keels(ships),...this was the number of ship loads that led to the foedus or treaty settlement. Gildas also uses in their correct sense technical terms, annona, epimenia, hospites, which most likely derive from official documents relating to the billeting and supply of barbarian foederati.
^ 7.07.17.2Morris. Age of Arthur. p.75. - Gildas:.. The federate complained that their monthly deliveries were inadequately paid.. - All the greater towns fell to their enemy..