This article looks at the origins of the army of Nader Shah (reigned 1736–1747) and the nature of the Persian armies in the Safavid period before considering in more detail the composition and structure of the army at its peak in the early 1740s. It suggests, building on work by Rudi Matthee, that it was only under Nader's tutelage that Persia fully embraced gunpowder weapons and that this initiated a Military Revolution (not just a revolution in technology, but in drill, discipline, and army size as well as ethos) that, but for Nader's untimely death, could have brought about the wider social and economic changes that Geoffrey Parker and others have associated with the Military Revolution in Europe.