From the autumn of 1917 onwards the SPAD XIII was used in ever increasing numbers on the Western Front by fighter units the French Air Force. After initially struggling over many "teething troubles", the bi-plane proved to be a serious adversary in the hands of experienced pilots with its twin machine-guns and 200hp in-line engine. It was not until the spring of 1918 however that after many modifications, it became fully operational and was produced in large numbers. Up to the German capitulation, US fighter pilots fighting in France had taken delivery of almost 900 of these aircraft.