From the 1970s historians began to emphasise that the English colonised America not by settlement but conquest. The lands of Amerindians were seized by force of arms, just as the Spanish had conquered Mexico and Peru. More recent studies have emphasised that English colonisers were uncomfortable with the language of conquest and employed natural law arguments that were more appropriate to agricultural settlers than to conquistadors. It is argued that these natural law claims underpinned the development of a commercial ideology of expansion. The use of the argument of terra nullius, for example, is said to reveal assumptions about the exploitation of the land that would underpin the expansion of commerce in the seventeenth and eighteenth centuries. Each of these interpretations, whether emphasising conquest or natural law, has drawn material from the early modern English tracts justifying colonisation to support their argument. Both would have that literature to be more coherent than it is. In fact, English promoters of colonies in the first century of colonising plans employed a whole battery of frequently conflicting arguments. These arguments were not only incoherent between authors and across time, but often the same author would resort to a range of mutually contradictory arguments. In this chapter I consider not only the use of ideas associated with the justification of agricultural colonies and conquest but also two arguments concerning the justification of colonies which have been ignored by historians.