Written in response to the threat of invasion by Catholic France and Spain in the early months of 1539, Richard Morison’s translation of Frontinus’s Strategemata is a paradigmatic example of translation for action in Tudor England. As Henry VIII’s propagandist, Morison used his translation to secure the king’s favour, but the translation is also of a piece with his evangelical fervour to defend the reformed English Church against its Catholic enemies. Morison’s Frontinus is unique in the range of responses surviving from the Tudor period, which reveal that Frontinus’s manual came to be associated with an ideology of Protestant nationalism through Morison’s translation. The chapter examines three readers who related the text to the war with France and Scotland in the mid-1540s and Gabriel Harvey’s marginal annotations to Morison’s Frontinus, which refer to the Spanish Armada of 1588 and reflect the religio-political agenda of military support for the international Protestant cause of his patron, the earl of Leicester.