This work examines, among other topics, the personal oath of loyalty that the officers of the German army swore to Adolf Hitler on August 2, 1934. It discusses how the majority of officers - those who did not become conspirators against him - complied with Hitler’s orders until May 1945 despite his cruel treatment of soldiers, militarily unsound strategy and tactics, and the widespread destruction and crimes he and his forces committed. The oath taken by the officers had a strong psychological effect among a proud corps with a long history of obedience and honor, causing them to follow Hitler until the end even though they knew they were fighting a losing battle.The author also examines why and how only a few officers, the conspirators, began to break away, lose trust in Hitler, oppose him and finally stage an assassination attempt. The work traces the development within the German army from 1918 of the philosophies of loyalty and disloyalty - and obedience and disobedience - as challenged by the Hitlerian oath of loyalty.