A cikin watan Fabrairun 1915, a kan jagorancin jam'iyyar SPD, an kira Liebknecht don aikin soja don kawar da shi, mataimakin SPD kawai da za a bi da shi. Saboda kokarinsa na shirya masu adawa da yaki, an fitar da shi daga SPD, kuma a watan Yunin 1916, an yanke masa hukuncin kisa a kan zargin babban cin amana zuwa shekaru hudu a kurkuku. Yayin da Liebknecht ke cikin sojojin, Rosa Luxemburg ya rubuta mafi yawan "Spartacus Letters". Bayan da aka yanke hukuncin kurkuku, an sake sanya ta a kurkuku a karkashin "kariya ta kariya" har sai yakin ya ƙare. Tambaya: Me yasa aka tura Liebknecht zuwa kurkuku?
babban cin amana