Gustav II Adolf, c. 1630, by Jakob Elbfas.
Gustav II was an great military innovator in his time. In addition to being well trained (Swedish troops were well disciplined and Swedish musketeers were both extremely accurate and unusually fast at reloading), Gustav II’s forces utilized an early form of combined arms tactics whereby cavalry, infantry, and artillery were used in coordination to shore up each other’s weak points. Swedish infantry were also used in very shallow formations (five or six ranks, contrasted to the more typical square formation with up to fifty ranks). Gustav II also used comparatively light bronze cannon which were unusually mobile and could be redeployed during a battle (which was unusual for the time). The Swedes also experimented with an extremely light “leather cannon” (a copper cannon reinforced with rope and leather) to bridge the gap between muskets and artillery, and although these proved to be a failure due to overheating they anticipated later developments in man-portable support guns.