The SPAD S.XIII was essentially an enlarged SPAD S.VII redesigned around a more powerful geared drive Hispano-Suiza engine, as used on the SPAD XII. This was produced in much greater numbers: the exact total is uncertain, with figures from 7,300 to 8,472 being quoted by different sources. Single-seat SPADs were flown by many ace pilots, including Italy's Count Francesco Baracca and the United States Army Air Service's Capt. Eddie Rickenbacker, with 34 and 26 victories respectively. Georges Guynemer was, as has already been noted, highly successful with the SPAD S.XII, as well as the SPAD S.VII and SPAD S.XIII. At the end of the First World War, all 1,152 single-seat fighters on the strength of French front line air units were SPAD 13s. Nearly 900 SPAD XIII fighters were reported as being used in American service.