This dissertation examines the intellectual and historical roots of the Anglo-American “Special Relationship,” most notably Anglo-Saxonism and social Darwinism, and their effect on the noted policy organs of the Royal Institute of International Affairs (or Chatham House) and the Council on Foreign Relations (or the Council). It first traces the origins of Anglo-Saxonism and considers its effect on important historical events such as the Spanish-American War and the Second Boer War. This thesis also presents a definition of Anglo-Saxonism which appreciates the complexity of the term and allows a better understanding of its effects. It then shows the memberships of both groups were strongly affected by these Victorian and Edwardian phenomena, a fact which augments our understanding of them. Furthermore, this relationship between Anglo-Saxonism and Chatham House and the Council is not fully appreciated by many modern academics. Ultimately, the language of Anglo-Saxonism developed during the Victorian and Edwardian eras became institutionalised during the formative years of these groups’ memberships, predisposing both to the importance of permanent Anglo-American cooperation.

In the fifth century, after the departure of the Romans, according to tradition, which is based on the ancient written sources, Britain was invaded by the Angles and Saxons. This view has been questioned in the last century. The size of the ‘invasion’, and indeed its very existence, have come into doubt. However, this doubting school of thought does not seem to take into account all of the evidence. An interdisciplinary, nuanced approach has been taken in this thesis. Firstly, the question of Germanic raiding has been examined, with reference to the Saxon Shore defences. It is argued that these defences, in their geographical context, point to the likelihood of raiding. Then the written sources have been re-examined, as well as physical artefacts. In addition to geography, literature and archaeology (the disciplines which are most commonly used when the coming of the Angles and Saxons is investigated), linguistic and genetic data have been examined. The fields of linguistics and genetics, which have not often both been taken into consideration with previous approaches, add a number of valuable insights. This nuanced approach yields a picture of events that rules out the ‘traditional view’ in some ways, such as the idea that the Saxons exterminated the Britons altogether, but corroborates it in other ways. There was an invasion of a kind (of Angles – not Saxons), who came in comparatively small numbers, but found in Britain a society already mixed and comprising Celtic and Germanic-speaking peoples: a society implied by Caesar and Tacitus and corroborated by linguistic and genetic data.