The most produced Japanese bomber of the war the G4M saw action on every front from the first day of the Pacific conflict through to VJ-Day. The 'Betty's' very long range made it a key weapon during the opening year of the war. However, to achieve this, the aircraft was built with very little protective armour for its crew or fuel tanks, and Allied pilots soon exposed its extreme vulnerability. In the first in a series of volumes examining the key Japanese aircraft of WW2, Dr Osamu Tagaya details the G4M's extensive combat history, and lists all the units which operated the bomber.