When Japanese tactics changed to elaborate reverse slope, multi-level, and interlocking cave defenses. This doctrinal difference is what lead to the Marine blood bath on Peleliu. Cave warfare was “low operational tempo” combat, a form of siege warfare with extensive field fortifications. Elaborate fortifications required elaborate scouting and elaborate, large scale, limited objective assaults with no real time constraints to yield gains at acceptable losses. It would take Peleliu, Iwo Jima and weeks of further combat on Okinawa, with the 6th Marine Division’s impalement on Sugarloaf, before the USMC’s Assault infantry doctrine yielded to it’s limited objective, methodical mass assault “Processing” tactics on Southern Okinawa in June 1945.I'd never heard of the aerial tramways, but it is a very clever engineering approach to help move tons of gear right up to the front line in mountainous terrain.
The methodical, artillery-centered, engineer informed, fighting culture of the US Army infantry division was well suited to dealing with Cave Warfare, when there were not senior naval commanders breathing down Army commander’s necks for early Central Pacific Drive Marine-like rapid advances, which happened to General Buckner’s 10th Army on Okinawa.
Only at Peleliu, with the island being declared “secure” and the 81st ID in the “Mop-up phase”, did we get to see a single Pacific Army Division’s organizational culture evolve in isolation to deal with Japanese “Cave Warfare” tactics. Effectively, what the 81st Infantry Division did was develop a “Sandbag Warfare Doctrine” to counter the “Cave Warfare Doctrine” by the Japanese. Each fighting position that the 81st ID occupied on Peleliu had filled sand bags. Sand bags sent up to them by these labor saving improvised aerial tramway’s.
The effect of these aerial tramway delivered sandbags was several fold. First, it took away much of the effectiveness of Japanese snipers and mortars, particularly their 50mm grenade dischargers, in producing a lot of American casualties.Long and detailed, this is excellent reading if you (like me) are a military history buff. Had it come to an invasion of the Japanese home islands, it might have been the Army's non-photogenic but practical tactics like these that would have won the day. Not at all what you normally hear in the histories.
Second, they gave American infantry a protected position to fight from with crew served heavy weapons (machine guns, mortars, light artillery) and artillery forward observers for Japanese counter attacks and infiltrations.
Third, it left American infantry _covered_ positions *closer* to Japanese positions to launch their “Blowtorch and corkscrew” flame/explosive attacks from. The 81st ID — unlike the 6th Marine Division at Sugar Loaf on Okinawa — didn’t have to cross the same ground over and over to get close enough to inflict attrition losses on underground Japanese positions. This was a very important development. At Biak, Leyte, Luzon, Tarawa, Saipan, Guam, Iwo Jima and Okinawa, flame thrower operators were dead men walking. This resulted in the U.S. Army’s Chemical Warfare Service having to train up a new generation of flamethrower operators for the next operation. This didn’t happen for the US Army after Peleliu. The 81st Infantry Division’s portable flamethrower operators actually survived the campaign. That was unheard of in Pacific Theater combat!