Lt Gen Jean-Jacques MUPENZI yavutse mu mwaka wa 1968, ubu ni Umugaba w’Ingabo z’u Rwanda zirwanira mu Kirere. Mu gihe cy’imyaka irenga 30 amaze mu gisirikare, yabaye umuyobozi w’ibyiciro bitandukanye mu ngabo harimo Batayo, Burigade na Diviziyo, haba mu bihe by’amahoro no mu bihe by’intambara. Yanabaye Umuyobozi Mukuru w’Ishuri Rikuru rya Gisirikare rya Nyakinama ndetse n’Umuyobozi wa Diviziyo y’Ingabo zikoresha imodoka z’intambara (Mechanized Division).

Lt Gen MUPENZI yitabiriye ndetse anasoza neza amasomo ya gisirikare mu Rwanda, mu karere no mu mahanga. Yize mu Ishuri rikuru rya Gisirikare rya Karen muri Kenya; yize amasomo ajyanye n’imiyoborere y’ingabo mu mashuri ya gisirikare mu Bwongereza, Nigeria no mu Bushinwa.

Lt Gen Jean-Jacques MUPENZI afite Impamyabumenyi y’icyiciro cya gatatu cya kaminuza mu bijyanye n’umutekano n’ubumenyi mu by’imibanire mpuzamahanga yakuye muri King’s College London mu Bwongereza no muri kaminuza zo muri Kenya. Afite kandi Impamyabumenyi y’icyiciro cya kabiri cya Kaminuza mu Miyoborere.

Lt Gen Jean-Jacques MUPENZI yabaye Umuyobozi w’Ingabo z’u Rwanda zari mu butumwa bw’amahoro bw’ Umuryango wa Afurika Yunze Ubumwe i Darfur, muri Sudan, yabaye kandi Umuyobozi w’Ingabo( Sector Commander) mu butumwa bw’amahoro bw’Umuryango w’Abibumbye muri Sudani y’Epfo.

Lt Gen MUPENZI yitabiriye ndetse agira uruhare mu myitozo ya gisirikare yari igamije guha ubushobozi bukwiye Ingabo za Afurika ziteguye gutabara ndetse n’Ingabo z’Umuryango wa Afurika y’Iburasirazuba ziteguye gutabara.

Yitabiriye kandi inama nyinshi n’ibiganiro byo ku rwego rwo hejuru, harimo ibyateguwe n’Ikigo Nyafurika cy’Ubushakashatsi cyashinzwe na Leta Zunze Ubumwe za Amerika, yanitabiriye amahugurwa agenerwa abayobozi bakuru mu kubongerera ubumenyi mu bijyanye no kubungabunga amahoro yabereye mu Kigo cya International Peace Support Training Centre muri Kenya.

Mu buzima bwite, Lt Gen MUPENZI arubatse. Akunda gukora siporo yo kwiruka (Jogging) no gusoma ibitabo bijyanye n’amateka ya gisirikare.