Kammala wannan jumla: Gosselin ya shiga Royal Navy a ranar 2 ga watan Agustan 1778 a matsayin mai bin Captain Philip Boteler a cikin sabon jirgin ruwa. Daga bisani sai ya canja tare da Kyaftin Boteler zuwa jirgin ruwa a watan Yuni 1779. A ranar 16 ga watan Agusta "Ardent" ya kama shi ta hanyar haɗin gwiwar Faransa da Mutanen Espanya kusa da Portsmouth. Gosselin ya shafe watanni uku a matsayin fursunonin yaƙi a Alençon. Bayan da aka sake shi ya shiga jirgin-na-layi, jirgin tutar Rear-Admiral Sir Samuel Hood, a ranar 11 ga Oktoba, 1780. A kan "Barfleur" Gosselin ya shiga cikin manyan ayyuka na juyin juya halin Amurka a matsayin wani ɓangare na rundunar Admiral Sir George Rodney, ciki har da
Yaƙin Fort Royal, Yaƙin Chesapeake, da Yaƙin Saint Kitts. Bayan wannan yaƙin Gosselin ya koma jirgin ruwa wanda ɗan'uwan Rear-Admiral Hood ya umurce shi, Kyaftin Alexander Hood. A cikin "Champion" Gosselin ya shiga cikin yakin Delaware Bay da yakin Saintes, inda babban jami'in Faransa François Joseph Paul de Grasse ya mika wuya. Gosselin ya kuma kasance a yakin da aka yi a Mona Passage inda rundunar soja a karkashin Rear-Admiral Hood ta kama wani jirgin Faransa mai tserewa, tare da "Champion" wanda ya kama wani jirgin ruwa na Faransa. A watan Yunin 1782 Gosselin ya canja tare da Kyaftin Hood zuwa jirgin ruwa mai suna HMS "Aimable", yana aiki a cikinta har sai juyin juya halin Amurka ya ƙare tare da Yarjejeniyar Paris a 1783. Ya koma gida a ranar 26 ga Yuni 1783.