 In Tasimboko , Edson 's troops discovered the supply base for Kawaguchi 's forces , including large stockpiles of food , ammunition and medical supplies , and a shortwave radio . The Marines seized documents , equipment and food supplies , destroyed the rest , and returned to the Lunga perimeter at 17 : 30 . The quantities of supplies and intelligence from the captured documents revealed that at least 3 @,@ 000 Japanese troops were on the island and apparently planning an attack .   Edson and Colonel Gerald Thomas , Vandegrift 's operations officer , believed that the Japanese attack would come at the Lunga Ridge , a narrow , grassy , 1 @,@ 000 m ( 1 @,@ 100 yd ) long , coral ridge ( 9 ° 26 ′ 39 ″ S 160 ° 2 ′ 50 ″ E ) parallel to the Lunga River just south of Henderson Field . The ridge offered a natural avenue of approach to the airfield , commanded the surrounding area and was almost undefended . Edson and Thomas tried to persuade Vandegrift to move forces to defend the ridge , but Vandegrift refused , believing that the Japanese were more likely to attack along the coast . Finally , Thomas convinced Vandegrift that the ridge was a good location for Edson 's Raiders to " rest " from their actions of the preceding month . On 11 September , the 840 men of Edson 's unit — including the 1st Raiders and the Paramarines — deployed onto and around the ridge and prepared to defend it .   Kawaguchi 's Center Body of troops was planning to attack the Lunga perimeter at the ridge , which they called " the centipede " ( mukade gata ) because of its shape . On 9 September , Kawaguchi 's troops left the coast at Koli Point . Split into four columns , they marched into the jungle towards their predesignated attack points south and southeast of the airfield . Lack of good maps , at least one faulty compass , and thick , almost impenetrable jungle caused the Japanese columns to proceed slowly and zigzag , costing a lot of time . At the same time , Oka 's troops approached the Lunga perimeter from the west . Oka had some intelligence on the Marine defenses , extracted from a U.S. Army pilot captured on 30 August .   During the day of 12 September , Kawaguchi 's troops struggled through the jungle toward their assembly points for that night 's attacks . Kawaguchi wanted his three Center Body battalions in place by 14 : 00 , but they did not reach their assembly areas until after 22 : 00 . Oka was also delayed in his advance towards the Marine lines in the west . Only the Kuma battalion reported that they were in place on time . Despite the problems in reaching the planned attack positions , Kawaguchi was still confident in his attack plan because a captured U.S. pilot disclosed that the ridge was the weakest part of the Marine defenses . Japanese bombers attacked the ridge during daytime on 11 – 12 September , causing a few casualties , including two killed .   = = = First night 's action = = =   The Americans knew of the approach of the Japanese forces from reports from native scouts and their own patrols , but did not know exactly where or when they would attack . The ridge around which Edson deployed his men consisted of three distinct hillocks . At the southern tip and surrounded on three sides by thick jungle was Hill 80 ( so named because it rose 80 ft ( 24 m ) above sea level ) . Six hundred yards north was Hill 123 ( 123 ft ( 37 m ) high ) , the dominant feature on the ridge . The northernmost hillock was unnamed and about 60 ft ( 18 m ) high . Edson placed the five companies from the Raider battalion on the west side of the ridge and the three Parachute battalion companies on the east side , holding positions in depth from Hill 80 back to Hill 123 . Two of the five Raider companies , " B " and " C " , held a line between the ridge , a small , swampy lagoon , and the Lunga River . Machine @-@ gun teams from " E " Company , the heavy weapons company , were scattered throughout the defenses . Edson placed his command post on Hill 123 .   At 21 : 30 on 12 September , the Japanese cruiser Sendai and three destroyers shelled the Lunga perimeter for 20 minutes and illuminated the ridge with a searchlight . Japanese artillery began shelling the Marine lines , but did little damage . At the same time , scattered groups of Kawaguchi 's troops began skirmishing with Marines around the ridge . Kawaguchi 's 1st Battalion — led by Major Yukichi Kokusho — attacked the Raider 's " C " company between the lagoon and the Lunga River , overrunning at least one platoon and forcing the Marine company to fall back to the ridge . Kokusho 's unit became entangled with troops from Kaw
ĠIn ĠTas imb oko Ġ, ĠEd son Ġ' s Ġtroops Ġdiscovered Ġthe Ġsupply Ġbase Ġfor ĠKaw ag uchi Ġ' s Ġforces Ġ, Ġincluding Ġlarge Ġstockp iles Ġof Ġfood Ġ, Ġammunition Ġand Ġmedical Ġsupplies Ġ, Ġand Ġa Ġshort wave Ġradio Ġ. ĠThe ĠMarines Ġseized Ġdocuments Ġ, Ġequipment Ġand Ġfood Ġsupplies Ġ, Ġdestroyed Ġthe Ġrest Ġ, Ġand Ġreturned Ġto Ġthe ĠLung a Ġperimeter Ġat Ġ17 Ġ: Ġ30 Ġ. ĠThe Ġquantities Ġof Ġsupplies Ġand Ġintelligence Ġfrom Ġthe Ġcaptured Ġdocuments Ġrevealed Ġthat Ġat Ġleast Ġ3 Ġ@ , @ Ġ000 ĠJapanese Ġtroops Ġwere Ġon Ġthe Ġisland Ġand Ġapparently Ġplanning Ġan Ġattack Ġ. Ġ Ġ ĠEd son Ġand ĠColonel ĠGerald ĠThomas Ġ, ĠVand eg rift Ġ' s Ġoperations Ġofficer Ġ, Ġbelieved Ġthat Ġthe ĠJapanese Ġattack Ġwould Ġcome Ġat Ġthe ĠLung a ĠRidge Ġ, Ġa Ġnarrow Ġ, Ġgrass y Ġ, Ġ1 Ġ@ , @ Ġ000 Ġm Ġ( Ġ1 Ġ@ , @ Ġ100 Ġy d Ġ) Ġlong Ġ, Ġcoral Ġridge Ġ( Ġ9 ĠÂ° Ġ26 ĠâĢ ² Ġ39 ĠâĢ ³ ĠS Ġ160 ĠÂ° Ġ2 ĠâĢ ² Ġ50 ĠâĢ ³ ĠE Ġ) Ġparallel Ġto Ġthe ĠLung a ĠRiver Ġjust Ġsouth Ġof ĠHenderson ĠField Ġ. ĠThe Ġridge Ġoffered Ġa Ġnatural Ġavenue Ġof Ġapproach Ġto Ġthe Ġair field Ġ, Ġcommanded Ġthe Ġsurrounding Ġarea Ġand Ġwas Ġalmost Ġund ef ended Ġ. ĠEd son Ġand ĠThomas Ġtried Ġto Ġpersuade ĠVand eg rift Ġto Ġmove Ġforces Ġto Ġdefend Ġthe Ġridge Ġ, Ġbut ĠVand eg rift Ġrefused Ġ, Ġbelieving Ġthat Ġthe ĠJapanese Ġwere Ġmore Ġlikely Ġto Ġattack Ġalong Ġthe Ġcoast Ġ. ĠFinally Ġ, ĠThomas Ġconvinced ĠVand eg rift Ġthat Ġthe Ġridge Ġwas Ġa Ġgood Ġlocation Ġfor ĠEd son Ġ' s ĠRaiders Ġto Ġ" Ġrest Ġ" Ġfrom Ġtheir Ġactions Ġof Ġthe Ġpreceding Ġmonth Ġ. ĠOn Ġ11 ĠSeptember Ġ, Ġthe Ġ840 Ġmen Ġof ĠEd son Ġ' s Ġunit ĠâĢĶ Ġincluding Ġthe Ġ1 st ĠRaiders Ġand Ġthe ĠParam ar ines ĠâĢĶ Ġdeployed Ġonto Ġand Ġaround Ġthe Ġridge Ġand Ġprepared Ġto Ġdefend Ġit Ġ. Ġ Ġ ĠKaw ag uchi Ġ' s ĠCenter ĠBody Ġof Ġtroops Ġwas Ġplanning Ġto Ġattack Ġthe ĠLung a Ġperimeter Ġat Ġthe Ġridge Ġ, Ġwhich Ġthey Ġcalled Ġ" Ġthe Ġcent ip ede Ġ" Ġ( Ġm uk ade Ġg ata Ġ) Ġbecause Ġof Ġits Ġshape Ġ. ĠOn Ġ9 ĠSeptember Ġ, ĠKaw ag uchi Ġ' s Ġtroops Ġleft Ġthe Ġcoast Ġat ĠK oli ĠPoint Ġ. ĠSplit Ġinto Ġfour Ġcolumns Ġ, Ġthey Ġmarched Ġinto Ġthe Ġjungle Ġtowards Ġtheir Ġpred es ign ated Ġattack Ġpoints Ġsouth Ġand Ġsoutheast Ġof Ġthe Ġair field Ġ. ĠLack Ġof Ġgood Ġmaps Ġ, Ġat Ġleast Ġone Ġfaulty Ġcompass Ġ, Ġand Ġthick Ġ, Ġalmost Ġimp en etr able Ġjungle Ġcaused Ġthe ĠJapanese Ġcolumns Ġto Ġproceed Ġslowly Ġand Ġz ig zag Ġ, Ġcosting Ġa Ġlot Ġof Ġtime Ġ. ĠAt Ġthe Ġsame Ġtime Ġ, ĠO ka Ġ' s Ġtroops Ġapproached Ġthe ĠLung a Ġperimeter Ġfrom Ġthe Ġwest Ġ. ĠO ka Ġhad Ġsome Ġintelligence Ġon Ġthe ĠMarine Ġdefenses Ġ, Ġextracted Ġfrom Ġa ĠU . S . ĠArmy Ġpilot Ġcaptured Ġon Ġ30 ĠAugust Ġ. Ġ Ġ ĠDuring Ġthe Ġday Ġof Ġ12 ĠSeptember Ġ, ĠKaw ag uchi Ġ' s Ġtroops Ġstruggled Ġthrough Ġthe Ġjungle Ġtoward Ġtheir Ġassembly Ġpoints Ġfor Ġthat Ġnight Ġ' s Ġattacks Ġ. ĠKaw ag uchi Ġwanted Ġhis Ġthree ĠCenter ĠBody Ġbatt alions Ġin Ġplace Ġby Ġ14 Ġ: Ġ00 Ġ, Ġbut Ġthey Ġdid Ġnot Ġreach Ġtheir Ġassembly Ġareas Ġuntil Ġafter Ġ22 Ġ: Ġ00 Ġ. ĠO ka Ġwas Ġalso Ġdelayed Ġin Ġhis Ġadvance Ġtowards Ġthe ĠMarine Ġlines Ġin Ġthe Ġwest Ġ. ĠOnly Ġthe ĠK uma Ġbattalion Ġreported Ġthat Ġthey Ġwere Ġin Ġplace Ġon Ġtime Ġ. ĠDespite Ġthe Ġproblems Ġin Ġreaching Ġthe Ġplanned Ġattack Ġpositions Ġ, ĠKaw ag uchi Ġwas Ġstill Ġconfident Ġin Ġhis Ġattack Ġplan Ġbecause Ġa Ġcaptured ĠU . S . Ġpilot Ġdisclosed Ġthat Ġthe Ġridge Ġwas Ġthe Ġweakest Ġpart Ġof Ġthe ĠMarine Ġdefenses Ġ. ĠJapanese Ġbombers Ġattacked Ġthe Ġridge Ġduring Ġdaytime Ġon Ġ11 ĠâĢĵ Ġ12 ĠSeptember Ġ, Ġcausing Ġa Ġfew Ġcasualties Ġ, Ġincluding Ġtwo Ġkilled Ġ. Ġ Ġ Ġ= Ġ= Ġ= ĠFirst Ġnight Ġ' s Ġaction Ġ= Ġ= Ġ= Ġ Ġ ĠThe ĠAmericans Ġknew Ġof Ġthe Ġapproach Ġof Ġthe ĠJapanese Ġforces Ġfrom Ġreports Ġfrom Ġnative Ġscouts Ġand Ġtheir Ġown Ġpatrols Ġ, Ġbut Ġdid Ġnot Ġknow Ġexactly Ġwhere Ġor Ġwhen Ġthey Ġwould Ġattack Ġ. ĠThe Ġridge Ġaround Ġwhich ĠEd son Ġdeployed Ġhis Ġmen Ġconsisted Ġof Ġthree Ġdistinct Ġhill ocks Ġ. ĠAt Ġthe Ġsouthern Ġtip Ġand Ġsurrounded Ġon Ġthree Ġsides Ġby Ġthick Ġjungle Ġwas ĠHill Ġ80 Ġ( Ġso Ġnamed Ġbecause Ġit Ġrose Ġ80 Ġft Ġ( Ġ24 Ġm Ġ) Ġabove Ġsea Ġlevel Ġ) Ġ. ĠSix Ġhundred Ġyards Ġnorth Ġwas ĠHill Ġ123 Ġ( Ġ123 Ġft Ġ( Ġ37 Ġm Ġ) Ġhigh Ġ) Ġ, Ġthe Ġdominant Ġfeature Ġon Ġthe Ġridge Ġ. ĠThe Ġnorthern most Ġhill ock Ġwas Ġunnamed Ġand Ġabout Ġ60 Ġft Ġ( Ġ18 Ġm Ġ) Ġhigh Ġ. ĠEd son Ġplaced Ġthe Ġfive Ġcompanies Ġfrom Ġthe ĠRaider Ġbattalion Ġon Ġthe Ġwest Ġside Ġof Ġthe Ġridge Ġand Ġthe Ġthree ĠPar ach ute Ġbattalion Ġcompanies Ġon Ġthe Ġeast Ġside Ġ, Ġholding Ġpositions Ġin Ġdepth Ġfrom ĠHill Ġ80 Ġback Ġto ĠHill Ġ123 Ġ. ĠTwo Ġof Ġthe Ġfive ĠRaider Ġcompanies Ġ, Ġ" ĠB Ġ" Ġand Ġ" ĠC Ġ" Ġ, Ġheld Ġa Ġline Ġbetween Ġthe Ġridge Ġ, Ġa Ġsmall Ġ, Ġswamp y Ġlag oon Ġ, Ġand Ġthe ĠLung a ĠRiver Ġ. ĠMachine Ġ@ - @ Ġgun Ġteams Ġfrom Ġ" ĠE Ġ" ĠCompany Ġ, Ġthe Ġheavy Ġweapons Ġcompany Ġ, Ġwere Ġscattered Ġthroughout Ġthe Ġdefenses Ġ. ĠEd son Ġplaced Ġhis Ġcommand Ġpost Ġon ĠHill Ġ123 Ġ. Ġ Ġ ĠAt Ġ21 Ġ: Ġ30 Ġon Ġ12 ĠSeptember Ġ, Ġthe ĠJapanese Ġcruiser ĠSend ai Ġand Ġthree Ġdestroy ers Ġshe lled Ġthe ĠLung a Ġperimeter Ġfor Ġ20 Ġminutes Ġand Ġilluminated Ġthe Ġridge Ġwith Ġa Ġsearch light Ġ. ĠJapanese Ġartillery Ġbegan Ġshelling Ġthe ĠMarine Ġlines Ġ, Ġbut Ġdid Ġlittle Ġdamage Ġ. ĠAt Ġthe Ġsame Ġtime Ġ, Ġscattered Ġgroups Ġof ĠKaw ag uchi Ġ' s Ġtroops Ġbegan Ġskirm ishing Ġwith ĠMarines Ġaround Ġthe Ġridge Ġ. ĠKaw ag uchi Ġ' s Ġ1 st ĠBattalion ĠâĢĶ Ġled Ġby ĠMajor ĠYuk ichi ĠKok ush o ĠâĢĶ Ġattacked Ġthe ĠRaider Ġ' s Ġ" ĠC Ġ" Ġcompany Ġbetween Ġthe Ġlag oon Ġand Ġthe ĠLung a ĠRiver Ġ, Ġover running Ġat Ġleast Ġone Ġplatoon Ġand Ġforcing Ġthe ĠMarine Ġcompany Ġto Ġfall Ġback Ġto Ġthe Ġridge Ġ. ĠKok ush o Ġ' s Ġunit Ġbecame Ġentangled Ġwith Ġtroops Ġfrom ĠKaw