The conflict, personal rivalry and contrast in personality, generalship and command, between the two iconic commanders in the Thirty Years War, King Gustavus Adolphus of Sweden for the Protestant powers, and Albrecht von Wallenstein, Duke of Friedland. More than just commanders at the tactical level they were statesmen, military organizers and strategists on a continental scale. Both commanders represented the 17th-century ‘military revolution in action’. The writing is vivid, graphic and detailed, without overloading, and readers can feel ‘involved’ in the action, from strategic planning to battlefield tactics, and even the melee. Both generals are titanic figures come, and their respective deaths - Gustavus heroically in battle and Wallenstein, murdered with the Emperor’s compliance – were dramatic highpoints in the long war. This is no hagiography, and the author analyses the contrasting reputations of two of the greatest military figures in modern history and analyses mistakes as well their triumphs. Both commanders’ understanding of the role of the modern state and finance as vital factors in the military revolution and modern warfare. A major contrast was Gustavus’s constant search for the tactical and strategic initiative compared to Wallenstein’s caution and patience and development of counter-punch defensive tactics. Exceptional for the period, a young warrior like an ‘Alexander’, Gustavus excelled in inspired battlefield leadership even at huge risk. Despite his death at Lutzen in 1632, he and his steadfast chancellor Oxenstierna, had decisively defeated the Emperor’s attempt to subjugate the Empire and introduce the Catholic counter-reformation. Gustavus contributed hugely to the ending of Habsburg supremacy while advancing new concepts in modern war. His death ushered in his acolytes including generals Baner, Saxe-Weimar and Torstensson. Gustavus or Wallenstein, the greater of the two? The reader must judge but Napoleon included Gustavus in his list of ten greats with Julius Caesar, Hannibal Barca, and Alexander the Great.