This article explores how changes in methods and intentions affected conflicts in the Atlantic world from the fifteenth to the eighteenth centuries. First, it defines war in this era — specifically, to distinguish between acts of war and other types of violence that occurred in the Atlantic world between 1440 and 1763. Although the peoples of the Atlantic world made war idiosyncratically in this era — shaping their uses of force to suit their particular social, technological, political, and cultural circumstances — all were to be touched by what historians term the Military Revolution. In comparison with Portugal, Spain had a much more substantial impact on the Atlantic warfare of the sixteenth century. In the second half of the seventeenth century, England took the lead in creating a fleet of specialised warships to defend its home waters and to protect its overseas trade and colonies. While England was leading at sea, France was building the largest and most powerful standing army in Europe. Fighting in America was sometimes linked to wars in Europe but was rarely limited by European military conventions.