 In the Thirty Years' War (1618-1648), Gustavus Adolphus of Sweden demonstrated advanced operational strategy that led to his victories on the soil of the Holy Roman Empire.It was not until the 18th century that military strategy was subjected to serious study in Europe.The word was first used in German as ""Strategie"" in a translation of Leo's work in 1777, shortly thereafter in French as ""stratégie"" by Leo's French translator, and was first attested in English 1810.