Rubuta ci gaba ga wannan sakin layi - Duke Charles ya shiga aikin Prussian a lokacin da yake matashi. A lokacin da yake da shekaru 19 ya gudanar da kwamiti a matsayin Kyaftin kuma a 1806 an ci gaba da shi zuwa Major. Ya yi yaƙi don surukinsa Sarki Frederick William III na Prussia a lokacin Yaƙin Ƙungiyar ta huɗu.
tare da sarki a cikin gudu bayan Prussian shan kashi a cikin Battle of Jena-Auerstedt. Don hidimarsa a yakin Saale Duke Charles ya sami lambar yabo ta Black Eagle.