Rubuta ci gaba ga wannan sakin layi - A cikin Austro-Prussian War Hassel ya shiga, a matsayin memba na a cikin yaƙe-yaƙe na Hühnerwasser da Münchengrätz
Ka yi haƙuri. A ranar 28 ga Yuli 1866 ya zama Kyaftin kuma an ba shi lambar yabo ta Order of the Crown. A watan Maris na 1870, yanzu kwamandan kwamandan, an sake tura Hasel, a wannan lokacin zuwa 35th Brandenburg Fusilier regiment. Tare da tattara wannan shekarar a kan Faransa, ya shiga Babban Jami'in na 16th Division. A wannan matsayin ya halarci yaƙe-yaƙe na Spicheren, Mars-la-Tour, Gravelotte, Amiens, Hallue da St. Quentin. Ya kuma shiga cikin nasarar Siege na Metz. An sake inganta Hassel a ranar 22 ga Disamba, 1870, yanzu ya zama Manjo, kuma ya ba da Iron Cross. Bayan yakin ya ƙare a hukumance ta Yarjejeniyar Frankfurt (1871), an tura shi zuwa Babban Jami'in Rundunar Sojoji ta 8.