This chapter explores the fate of obstinate enemy garrisons who chose to withstand British breach assaults in the Napoleonic era. Under customary laws of war, British soldiers had the right to put such garrisons to the sword. In the sieges of the Peninsular War, British soldiers generally gave mercy to their French counterparts, part of a consistent pattern of self-regulating restraint that characterised Anglo-French combat during the war. A shared Anglo-French martial culture of honour and civility prevailed. Amongst other national enemies, however, in other contemporary global theatres of war, a very different picture emerges. British soldiers put defending Spanish and Indian troops to the sword at the sieges of Montevideo, Seringapatam and Gawilghur, raising important questions about the complex ways in which military and cultural factors coalesced, in shaping patterns of restraint and excess. These comparative case studies reveal the paradoxical Janus-face of enlightened ‘civilized war’ in action, with moderation and protections accorded to those enemy soldiers who fell firmly within its self-defining and self-limiting boundaries, and a dramatic lowering of restraints towards those combatants deemed to be on its margins or beyond.