sentences:  Following the victory of Éamon de Valera in East Clare, while standing for Sinn Féin, on 10 July 1917, Ginnell joined Sinn Féin.At the Sinn Féin Ard Fheis that year, at which the party was re-constituted as a Republican party with de Valera as President, Ginnell and W. T. Cosgrave were elected Honorary Treasurers.He was imprisoned in March 1918 for encouraging land agitation, and later deported to Reading Gaol.