Ultima ratio regum is Latin for The last argument of kings
ultima ratio regum The final argument of kings. Louis XIV of France, recognized that force is the final argument, so he directed that his cannons carry the engraving 'ultima ratio regum' (1650). As a result, this phrase usually signifies 'war' or 'the use of military weapons; force'. The phrase was adopted in the form of 'Ultima ratio regis' for th...
the final argument of kings (a resort to arms): motto engraved on the cannon of Louis XIV.