Rubuta ci gaba ga wannan sakin layi - A shekara ta 1810 Boyen ya zama Daraktan Majalisar Soja. A cikin sake kafa rundunar sojojin Prussian ya yi aiki a matsayin mai taimakawa Scharnhorst mafi himma, amma bayan kammala yarjejeniyar tsakanin Prussia da Faransa a 1812 ya yi murabus daga mukaminsa a matsayin colonel kuma ya ziyarci Vienna da St Petersburg. Abubuwan da suka faru na 1813 sun gan shi ya sake komawa sabis na Prussian: a matsayin colonel ya bi sojojin Rasha daga sansaninsa a Kalisz zuwa Saxony. Bayan Yaƙin Lützen
(2 Mayu 1813) ya kasance mai kula da masu tsaron kan iyaka kuma a ƙarshe ya kare Berlin. Amma a lokacin yarjejeniyar King Frederick William III ya nada shi Shugaban Janar na Janar na 3rd Army Corps. Kamar yadda irin wannan, Boyen ya shiga cikin fadace-fadace da rikice-rikice na 1813 da 1814 kuma ya sami ci gaba ga babban janar.