 On 5 February 1944, Brigadier Bernard Fergusson's 16th Brigade set out from Ledo, on foot.They crossed exceptionally difficult terrain which the Japanese had not guarded, and penetrated the Japanese rear areas.In early March, three other brigades were flown into landing zones behind Japanese lines by the USAAF 1st Air Commando Group, from where they established strongholds on most of the Japanese road and rail links to their northern front.