 With Ireland having become embroiled in the Great War Kettle returned to Dublin.On arrival back home he sided with the National Volunteers in a split within the Irish Volunteers nationalist militia's ranks between those for whom Irish independence was all, and were increasingly eying the possibility an armed confrontation with the British Government (with the threat of an armed insurrection against Irish Nationalism from Ulster having abated with the Ulster Volunteers having enlisted en masse into the British Army to fight in World War 1), and those who followed John Redmond's constitutional lead in accepting the Government of the United Kingdom's public undertaking of a restoration of self-government to Ireland in its domestic affairs, temporarily deferred until the war's end, and who were also concerned about matters beyond Ireland's shores with Europe's future in the 20th Century now being decided.In consequence Kettle volunteered for active service with the 7th Battalion of the Leinster Regiment, but was refused on the grounds of fragile health.