Kammala jumla mai zuwa: Bayan shigar Amurka cikin Yaƙin Duniya na I, a watan Afrilu 1917, an sanya Middleton zuwa Rukunin Sojoji na 4, kuma ba da daɗewa ba ya ga aikin a matsayin kwamandan bataliya a lokacin yakin
Yaƙin Marne na biyu. Bayan watanni uku, bayan wasu ƙananan ayyuka na tallafi, ƙungiyarsa ta jagoranci harin a lokacin Meuse-Argonne Offensive, kuma Middleton ya zama kwamandan kwamandan. Saboda kwarewarsa a fagen fama, a ranar 14 ga Oktoba 1918 an ba shi mukamin Kanar, ya zama, yana da shekaru 29, mafi karancin shekaru a wannan mukamin a cikin Sojojin Amurka (AEF). Ya kuma sami lambar yabo ta Sojoji don aikinsa na misali. Bayan Yaƙin Duniya na I, Middleton ya yi aiki a Makarantar Sojojin Amurka ta Sojojin Amurka, da Rundunar Sojojin Amurka da Makarantar Janar, da Kwalejin Sojan Amurka, kuma a matsayin kwamandan 'yan takara a LSU. Ya yi ritaya daga rundunar a 1937 don zama shugaban sashen gudanarwa kuma daga baya mai kula da kuma mataimakin shugaban kasa a LSU. Zamaninsa a LSU yana cike da wahala, yayin da Middleton ya zama ɗaya daga cikin manyan 'yan wasa wajen taimaka wa jami'ar ta farfaɗo daga babban abin kunya inda aka ɓoye kusan dala miliyan.