The principal pursuit planes of the Air Service were the MB-3 (50 in inventory), the MB-3A (200 acquired 1920–23), and the Curtiss PW-8/P-1 Hawk (48 acquired in 1924–25). The only bomber ordered in quantity was the Martin NBS-1 (130 ordered 1920–1922), the mass-produced version of the MB-2 bomber developed in 1920. Mitchell used the NBS-1 as the primary striking weapon during his demonstration in July 1921 off the Virginia coast that resulted in the sinking of the captured German battleship "Ostfriesland".