Rubuta ci gaba don wannan sakin layi - Clarke na ɗaya daga cikin manyan janar-janar na Franco-Irish da suka fi tasiri a cikin sojojin Faransa a lokacin mulkin Napoleon. Yana da kusanci da Brigade na Irish na Faransa. Mahaifinsa ya yi aiki a Dillon's Regiment (inda Clarke da kansa ya yi aiki na ɗan lokaci) kuma mahaifin mahaifiyarsa da kawunsa da yawa sun yi aiki a Clare's Regiment. Da barkewar juyin juya halin Faransa, Clarke ya yi aiki a farkon yakin juyin juya halin Faransa a cikin Rundunar Rhine, kuma a shekara ta 1793 an daukaka shi zuwa "général de brigade". A shekara ta 1795 an kama Clarke na ɗan gajeren lokaci. Bayan da aka sake shi, Clarke ya zauna a Alsace har sai Lazare Carnot ya aike shi zuwa Italiya don ya zama babban jami'in Napoleon Bonaparte, har sai an aika shi zuwa Sardinia. Bayan 18 Brumaire, Clarke ya yi aiki a matsayin Shugaban Ofishin Topographical, Kwamishinan Jiha, sakataren jiha na rundunar soji da na sojan ruwa. A lokacin yakin da Austria a 1805, an nada Clarke gwamnan Vienna kuma a lokacin yakin da Prussia
a cikin 1806 ya yi aiki a matsayin gwamnan Erfurt da na Berlin.