 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 .   Meanwhile , the previous day , 3 May , the 57th / 60th Infantry Battalion had begun operating along the parallel Commando Road to the north . Here they had a number of encounters and suffered casualties due to their inexperience in patrolling , which resulted in them being ambushed . They also kept up a steady advance and eventually beat the main force in reaching , and crossing the river , arriving there on 6 May . On 5 May , along the Buin Road , the 24th Infantry Battalion had pressed forward again . Advancing with a tank troop in support , they came up against a concealed field gun defended by approximately 100 Japanese . After the lead Matilda 's machine gun jammed , the field gun opened fire on it , damaging it and wounding its crew . Moving around the stricken tank , the second Matilda , armed with a howitzer , opened fire and destroyed the field gun before sweeping the Japanese defenders from the position . That night , the Japanese artillery opened up on the Australian position with a heavy barrage , and the following morning put in a company @-@ sized counter @-@ attack . The fighting lasted for over two @-@ and @-@ a @-@ half hours , but when it was over the Australians remained in possession of the position having repulsed the attack . In doing so , they suffered one killed and nine wounded , while the attacking Japanese had suffered heavily , losing 58 men killed . It was the biggest loss since the action at Slater 's Knoll and it spelt the end of their attempt to defend the Hongorai .   After this , the Australians were able to resume their advance to the river on 7 May without further opposition . The previous three weeks in which they had advanced 7 @,@ 000 yd ( 6 @,@ 400 m ) to the Hongorai had been costly for them , however , with the Australian 24th Infantry Battalion losing 25 killed and 95 wounded . Against this , the Japanese had lost at least 169 killed .   = = = Crossing the Hongorai = = =   Following the advance to the Hongorai , there was a pause of about a week as the Australians had to wait for roads to be improved and supplies to be brought up , before attempting to cross the Hongorai en masse . This allowed Savige to re @-@ evaluate the situation and to issue new orders for the advance towards the Hari and Mivo Rivers . As they waited for the advance to resume , the Australians carried out reconnaissance patrols deep into Japanese held territory and there were a couple of significant engagements during this time . As a part of these , the 24th Infantry Battalion sent a company across the Hongorai and subsequently located a strong Japanese position on a feature that became known as Egan 's Ridge , which , due to its location , commanded the main Australian axis of advance .   The main crossing was planned for 20 May , with the 58th / 59th Infantry Battalion on the right tasked to cut the Buin Road and the Aitara Track to the east of the river , while on the left the 57th / 60th Infantry Battalion would divert the attention of the Japanese off the 24th Infantry Battalion which would make the main frontal assault from the centre of the Australian line , crossing at the Pororei ford , advancing straight up the Buin Road . Preliminary moves began before this , and on 15 May a platoon from the 24th Infantry Battalion along with two tanks attempted to carry out an attack on Egan 's Ridge . After one of the tanks was held up and knocked out by a Japanese field gun , they were forced to withdraw . Meanwhile , the RNZAF Corsair squadrons — now reinforced by No. 16 Squadron — began an eight @-@ day aerial campaign , attacking along the length of the Buin and Commando Roads . During this period , the New Zealanders flew 381 sorties , while artillery and mortars fired " thousands of rounds
Ġas Ġa Ġcreeping Ġbarrage Ġof Ġartillery Ġand Ġmortar Ġfire Ġ. ĠWith Ġsuch Ġstrong Ġsupport Ġthe ĠJapanese Ġoffered Ġlittle Ġresistance Ġand Ġover Ġthe Ġcourse Ġof Ġtwo Ġdays Ġthe Ġ24 th ĠInfantry ĠBattalion Ġcovered Ġalmost Ġa Ġthird Ġof Ġthe Ġdistance Ġto Ġthe ĠHong or ai Ġ, Ġfor Ġjust Ġone Ġman Ġwounded Ġ. ĠFurther Ġprogress Ġwas Ġmade Ġover Ġthe Ġnext Ġweek Ġ, Ġbut Ġon Ġ4 ĠMay Ġthe Ġadvance Ġwas Ġslowed Ġwhen Ġthey Ġencountered Ġa Ġroad block Ġdefended Ġby Ġa Ġfield Ġgun Ġalong Ġwith Ġa Ġmachine Ġgun Ġ, Ġmines Ġand Ġother Ġimprovised Ġexplosive Ġdevices Ġ. ĠAfter Ġthis Ġ, Ġthe Ġ15 th ĠBrigade Ġ' s Ġengineer Ġsupport Ġwere Ġcalled Ġupon Ġto Ġregularly Ġcarry Ġout Ġroute Ġclearance Ġand Ġproving Ġoperations Ġas Ġthe ĠJapanese Ġbecame Ġincreasingly Ġdesperate Ġto Ġdestroy Ġthe ĠAustralian Ġarmour Ġ, Ġto Ġthe Ġextent Ġthat Ġthey Ġwere Ġprepared Ġto Ġsacrifice Ġan Ġartillery Ġpiece Ġin Ġorder Ġto Ġlure Ġthe ĠAustralian Ġtanks Ġinto Ġa Ġtrap Ġwhere Ġthey Ġcould Ġbe Ġdestroyed Ġby Ġmines Ġ. ĠThe ĠJapanese Ġbegan Ġto Ġadapt Ġtheir Ġtactics Ġin Ġother Ġways Ġalso Ġ. ĠTo Ġnegate Ġthe Ġeffectiveness Ġof Ġthe ĠAustralian Ġtanks Ġ, Ġthe ĠJapanese Ġbegan Ġto Ġposition Ġthemselves Ġoff Ġthe Ġroads Ġ, Ġforcing Ġthe Ġinfantry Ġto Ġfight Ġwithout Ġtheir Ġarmoured Ġsupport Ġ. ĠAdditionally Ġ, Ġthe ĠJapanese Ġbegan Ġto Ġconcentrate Ġtheir Ġartillery Ġwith Ġincreasing Ġaccuracy Ġupon Ġthe Ġadvancing Ġinfantry Ġ, Ġwhich Ġthey Ġkept Ġunder Ġconstant Ġobservation Ġand Ġfire Ġ. Ġ Ġ ĠMeanwhile Ġ, Ġthe Ġprevious Ġday Ġ, Ġ3 ĠMay Ġ, Ġthe Ġ57 th Ġ/ Ġ60 th ĠInfantry ĠBattalion Ġhad Ġbegun Ġoperating Ġalong Ġthe Ġparallel ĠCommando ĠRoad Ġto Ġthe Ġnorth Ġ. ĠHere Ġthey Ġhad Ġa Ġnumber Ġof Ġencounters Ġand Ġsuffered Ġcasualties Ġdue Ġto Ġtheir Ġinexper ience Ġin Ġpatrolling Ġ, Ġwhich Ġresulted Ġin Ġthem Ġbeing Ġamb ushed Ġ. ĠThey Ġalso Ġkept Ġup Ġa Ġsteady Ġadvance Ġand Ġeventually Ġbeat Ġthe Ġmain Ġforce Ġin Ġreaching Ġ, Ġand Ġcrossing Ġthe Ġriver Ġ, Ġarriving Ġthere Ġon Ġ6 ĠMay Ġ. ĠOn Ġ5 ĠMay Ġ, Ġalong Ġthe ĠBu in ĠRoad Ġ, Ġthe Ġ24 th ĠInfantry ĠBattalion Ġhad Ġpressed Ġforward Ġagain Ġ. ĠAdv ancing Ġwith Ġa Ġtank Ġtroop Ġin Ġsupport Ġ, Ġthey Ġcame Ġup Ġagainst Ġa Ġconcealed Ġfield Ġgun Ġdefended Ġby Ġapproximately Ġ100 ĠJapanese Ġ. ĠAfter Ġthe Ġlead ĠMat ilda Ġ' s Ġmachine Ġgun Ġjammed Ġ, Ġthe Ġfield Ġgun Ġopened Ġfire Ġon Ġit Ġ, Ġdamaging Ġit Ġand Ġwounding Ġits Ġcrew Ġ. ĠMoving Ġaround Ġthe Ġstricken Ġtank Ġ, Ġthe Ġsecond ĠMat ilda Ġ, Ġarmed Ġwith Ġa Ġhow itzer Ġ, Ġopened Ġfire Ġand Ġdestroyed Ġthe Ġfield Ġgun Ġbefore Ġsweeping Ġthe ĠJapanese Ġdefenders Ġfrom Ġthe Ġposition Ġ. ĠThat Ġnight Ġ, Ġthe ĠJapanese Ġartillery Ġopened Ġup Ġon Ġthe ĠAustralian Ġposition Ġwith Ġa Ġheavy Ġbarrage Ġ, Ġand Ġthe Ġfollowing Ġmorning Ġput Ġin Ġa Ġcompany Ġ@ - @ Ġsized Ġcounter Ġ@ - @ Ġattack Ġ. ĠThe Ġfighting Ġlasted Ġfor Ġover Ġtwo Ġ@ - @ Ġand Ġ@ - @ Ġa Ġ@ - @ Ġhalf Ġhours Ġ, Ġbut Ġwhen Ġit Ġwas Ġover Ġthe ĠAustralians Ġremained Ġin Ġpossession Ġof Ġthe Ġposition Ġhaving Ġrep uls ed Ġthe Ġattack Ġ. ĠIn Ġdoing Ġso Ġ, Ġthey Ġsuffered Ġone Ġkilled Ġand Ġnine Ġwounded Ġ, Ġwhile Ġthe Ġattacking ĠJapanese Ġhad Ġsuffered Ġheavily Ġ, Ġlosing Ġ58 Ġmen Ġkilled Ġ. ĠIt Ġwas Ġthe Ġbiggest Ġloss Ġsince Ġthe Ġaction Ġat ĠSlater Ġ' s ĠKn oll Ġand Ġit Ġsp elt Ġthe Ġend Ġof Ġtheir Ġattempt Ġto Ġdefend Ġthe ĠHong or ai Ġ. Ġ Ġ ĠAfter Ġthis Ġ, Ġthe ĠAustralians Ġwere Ġable Ġto Ġresume Ġtheir Ġadvance Ġto Ġthe Ġriver Ġon Ġ7 ĠMay Ġwithout Ġfurther Ġopposition Ġ. ĠThe Ġprevious Ġthree Ġweeks Ġin Ġwhich Ġthey Ġhad Ġadvanced Ġ7 Ġ@ , @ Ġ000 Ġy d Ġ( Ġ6 Ġ@ , @ Ġ400 Ġm Ġ) Ġto Ġthe ĠHong or ai Ġhad Ġbeen Ġcostly Ġfor Ġthem Ġ, Ġhowever Ġ, Ġwith Ġthe ĠAustralian Ġ24 th ĠInfantry ĠBattalion Ġlosing Ġ25 Ġkilled Ġand Ġ95 Ġwounded Ġ. ĠAgainst Ġthis Ġ, Ġthe ĠJapanese Ġhad Ġlost Ġat Ġleast Ġ169 Ġkilled Ġ. Ġ Ġ Ġ= Ġ= Ġ= ĠCrossing Ġthe ĠHong or ai Ġ= Ġ= Ġ= Ġ Ġ ĠFollowing Ġthe Ġadvance Ġto Ġthe ĠHong or ai Ġ, Ġthere Ġwas Ġa Ġpause Ġof Ġabout Ġa Ġweek Ġas Ġthe ĠAustralians Ġhad Ġto Ġwait Ġfor Ġroads Ġto Ġbe Ġimproved Ġand Ġsupplies Ġto Ġbe Ġbrought Ġup Ġ, Ġbefore Ġattempting Ġto Ġcross Ġthe ĠHong or ai Ġen Ġmasse Ġ. ĠThis Ġallowed ĠSav ige Ġto Ġre Ġ@ - @ Ġevaluate Ġthe Ġsituation Ġand Ġto Ġissue Ġnew Ġorders Ġfor Ġthe Ġadvance Ġtowards Ġthe ĠHar i Ġand ĠM ivo ĠRivers Ġ. ĠAs Ġthey Ġwaited Ġfor Ġthe Ġadvance Ġto Ġresume Ġ, Ġthe ĠAustralians Ġcarried Ġout Ġreconnaissance Ġpatrols Ġdeep Ġinto ĠJapanese Ġheld Ġterritory Ġand Ġthere Ġwere Ġa Ġcouple Ġof Ġsignificant Ġengagements Ġduring Ġthis Ġtime Ġ. ĠAs Ġa Ġpart Ġof Ġthese Ġ, Ġthe Ġ24 th ĠInfantry ĠBattalion Ġsent Ġa Ġcompany Ġacross Ġthe ĠHong or ai Ġand Ġsubsequently Ġlocated Ġa Ġstrong ĠJapanese Ġposition Ġon Ġa Ġfeature Ġthat Ġbecame Ġknown Ġas ĠE gan Ġ' s ĠRidge Ġ, Ġwhich Ġ, Ġdue Ġto Ġits Ġlocation Ġ, Ġcommanded Ġthe Ġmain ĠAustralian Ġaxis Ġof Ġadvance Ġ. Ġ Ġ ĠThe Ġmain Ġcrossing Ġwas Ġplanned Ġfor Ġ20 ĠMay Ġ, Ġwith Ġthe Ġ58 th Ġ/ Ġ59 th ĠInfantry ĠBattalion Ġon Ġthe Ġright Ġtasked Ġto Ġcut Ġthe ĠBu in ĠRoad Ġand Ġthe ĠA it ara ĠTrack Ġto Ġthe Ġeast Ġof Ġthe Ġriver Ġ, Ġwhile Ġon Ġthe Ġleft Ġthe Ġ57 th Ġ/ Ġ60 th ĠInfantry ĠBattalion Ġwould Ġdivert Ġthe Ġattention Ġof Ġthe ĠJapanese Ġoff Ġthe Ġ24 th ĠInfantry ĠBattalion Ġwhich Ġwould Ġmake Ġthe Ġmain Ġfrontal Ġassault Ġfrom Ġthe Ġcentre Ġof Ġthe ĠAustralian Ġline Ġ, Ġcrossing Ġat Ġthe ĠPor ore i Ġfor d Ġ, Ġadvancing Ġstraight Ġup Ġthe ĠBu in ĠRoad Ġ. ĠPrel iminary Ġmoves Ġbegan Ġbefore Ġthis Ġ, Ġand Ġon Ġ15 ĠMay Ġa Ġplatoon Ġfrom Ġthe Ġ24 th ĠInfantry ĠBattalion Ġalong Ġwith Ġtwo Ġtanks Ġattempted Ġto Ġcarry Ġout Ġan Ġattack Ġon ĠE gan Ġ' s ĠRidge Ġ. ĠAfter Ġone Ġof Ġthe Ġtanks Ġwas Ġheld Ġup Ġand Ġknocked Ġout Ġby Ġa ĠJapanese Ġfield Ġgun Ġ, Ġthey Ġwere Ġforced Ġto Ġwithdraw Ġ. ĠMeanwhile Ġ, Ġthe ĠR NZ AF ĠCorsair Ġsquad rons ĠâĢĶ Ġnow Ġreinforced Ġby ĠNo . Ġ16 ĠSquadron ĠâĢĶ Ġbegan Ġan Ġeight Ġ@ - @ Ġday Ġaerial Ġcampaign Ġ, Ġattacking Ġalong Ġthe Ġlength Ġof Ġthe ĠBu in Ġand ĠCommando ĠRoads Ġ. ĠDuring Ġthis Ġperiod Ġ, Ġthe ĠNew ĠZealand ers Ġflew Ġ38 1 Ġsort ies Ġ, Ġwhile Ġartillery Ġand Ġmort ars Ġfired Ġ" Ġthousands Ġof Ġrounds