Kammala jumla mai zuwa: Kiernan ya dage kan shiga cikin rundunar soji, kuma a wannan matsayin an nada shi Major a cikin 6th Missouri. A watan Mayu na shekara ta 1863 a
Port Gibson, Missouri, an ji masa rauni a huhu na hagu kuma an bar shi a filin don ya mutu. Da aka dawo da shi kuma aka tsare shi, ya yi gudun hijira zuwa sojojin Union kuma ya yi murabus daga mukaminsa. A ranar 1 ga Agusta 1863 Shugaba Abraham Lincoln ya ba shi izinin zama Brigadier Janar na Masu Sa kai; yana ba da umarni a wani matsayi a Miliken's Bend a kan Mississippi. Koyaya rashin lafiya sakamakon raunin da ya samu a fagen yaƙi ya tilasta masa yin murabus a ranar 3 ga Fabrairu, 1864.