A good story of this order of monks soldiers, since their creation in Palestine until the secularization of Prussia Albert of Brandenburg in 1525. The Livonian period of the order (especially from its merger with the Livonian Brothers of the Sword in 1237) seemed the most interesting and gives a good view of the history of the Baltic countries and the often conflictual relations between Germans, Poles and Balts, even if it's a Polish duke who invited the Teutonic Knights in Prussia.
Amusing detail, the author gives as historical existence of the Priory of Sion, including two grand masters were also grand masters of the Teutonic Knights (Charles of Lorraine and Maximilian), while the imaginary Priory is a literary hoax that serves the basis for the legend of the "Da Vinci Code"!