Resuming their advance , the Australians were supported by three squadrons of Corsairs from the Royal New Zealand Air Force — Nos. 14 , 22 and 26 Squadrons — which bombed and strafed the ground in front of the advancing infantry , as well as a creeping barrage of artillery and mortar fire . With such strong support the Japanese offered little resistance and over the course of two days the 24th Infantry Battalion covered almost a third of the distance to the Hongorai , for just one man wounded . Further progress was made over the next week , but on 4 May the advance was slowed when they encountered a roadblock defended by a field gun along with a machine gun , mines and other improvised explosive devices . After this , the 15th Brigade 's engineer support were called upon to regularly carry out route clearance and proving operations as the Japanese became increasingly desperate to destroy the Australian armour , to the extent that they were prepared to sacrifice an artillery piece in order to lure the Australian tanks into a trap where they could be destroyed by mines . The Japanese began to adapt their tactics in other ways also . To negate the effectiveness of the Australian tanks , the Japanese began to position themselves off the roads , forcing the infantry to fight without their armoured support . Additionally , the Japanese began to concentrate their artillery with increasing accuracy upon the advancing infantry , which they kept under constant observation and fire .