His 1576 was the first volume in an unfinished series planned to advocate for the establishment of English colonies abroad. In a symbolic frontispiece, Dee included a figure of Britannia kneeling by the shore beseeching Elizabeth I to protect her nation by strengthening her navy. Dee used Geoffrey's inclusion of Ireland in King Arthur's conquests to argue that Arthur had established a "British empire" abroad. He argued that the establishment of new colonies would benefit England economically, with said colonies being protected by a strong navy. Dee has been credited with coining the term British Empire, but Humphrey Llwyd has also been credited with the first use in his Commentarioli Britannicae Descriptionis Fragmentum, published eight years earlier in 1568.
