1866 - 20c on 15c light blue, Type I horseshoe ove

 1866 - 20c on 15c light blue, Type I horseshoe overprint with ‘XXVI’ dotted numeral cancellation on cover addressed to Gropello (23). Rare cover, exceptionally lacking the double-circle military mail handstamp that was normally paired with the numeral cancellation of the stamp. Unique recorded example. Carra-Carraro study, 18 recorded documents. Manzoni certificate