Hans-Alexander von Voss, born in Berlin in 1907, was one of those courageous staff officers who tried to overthrow the National Socialist regime by killing the dictator. Scholars, however, have not given him the credit he deserves. Von Voss was involved in two intended pistol attacks; one planned by the resistance group within the staff of field marshall Erich von Witzleben in Saint Germain at the beginning of 1941, the other thought up by the officers around Henning von Tresckow, who was a good friend of his, in March 1943. He tried to win the commanders-in-chief for the resistance on several occasions, but without success. As he was one of the conspirators of July 20th, 1944, and as he was aware of the Gestapo's methods of investigation, he committed suicide on October 8th, 1944. This study is based in particular on the unpublished letters that von Voss wrote to his wife, Gisela, nee von Stulpnagel. It was possible to both reconstruct the circumstances of his military career in the famous IR 9 up to lieutenant colonel, and to show how his doubts and criticism of the regime developed, which made him become a member of the resistance against Hitler. The letters reflect his political, religious and ethical beliefs, which motivated his actions against the regime and the dictator himself.