Why are the nine years of destructive invasion and attempted conquest of Scotland unknown to English literary criticism? This chapter shows why we have forgotten this unusually brutal invasive war of 1542–1550 and why it matters to remember it. It introduces the ‘British history’ of Geoffrey of Monmouth, through which English kings claimed feudal overlordship of Scotland. It shows how Henry VIII deployed Geoffrey’s history in his Declaration of 1542 to justify invasion, but also how Henry’s rhetoric and strategy disavowed any desire to conquer in the pretence that he was reluctantly forced into reminding the Scots of English overlordship. Such rhetoric, subsequently repeated and reprinted, helped both justify English claims and trivialise the war to the point of oblivion in modern English historiography. The chapter reads a neglected Scottish text by William Lamb which, opposing Henry’s claims by appealing to the law of nations, exposes the precarious fictionality of English claims to overlordship and its lack of credibility in a broader European context.