 With their long range and excellent low-altitude performance, they were employed effectively for tactical reconnaissance and ground-attack duties over the English Channel, but were thought to be of limited value as fighters due to their poor performance above .RAF Mustangs (Mk Is, which were not drop tank capable) made history on October 22, 1942 when they escorted 22 Wellington bombers on a daylight raid to Germany, thus becoming the first RAF single-seat fighters to fly over the country during World War II.The first American order for 150 P-51s, designated NA-91 by North American, was placed by the Army on 7 July 1940.