Iwo Jima with more Japanese prep?

I think I'm proof against rehashing any old topics, after a search here https://www.alternatehistory.com/forum/search/3415343/?q=iwo+jima&o=date&c[title_only]=1

https://en.wikipedia.org/wiki/Battle_of_Iwo_Jima
  • The tunnel linking the mountain to the main forces was never completed
  • The day the Americans invaded, 11 miles of a planned 17 miles of tunnel network had been dug.
  • The Japanese supply was inadequate. Troops were supplied a 60% of the standard issue of ammunitions sufficient for one engagement by one division, and food and forage enough for four months.
  • IJA had 21,060 total men under arms vs. 110,000 USMC men
So, let's give the Japanese the following:
  • Tunnels are completed as designed
  • Troops have sufficient ammunition and food
  • 50,000 IJA troops
How is the battle impacted? It's still going to be a loss for the IJA of course.
 
It delays the inevitable, kills more Americans, perhaps delays the invasion of Okinawa?

Pretty much this. Japanese resistance had already turned what was estimated to be a three-month cakewalk into a month-long slog. More preparation would simple increase the death toll, but I'm afraid nothing short of Amaterasu the ASB stealing Little Boy and Fat Man from the Americans is going to make FDR or Truman even consider negotiating a conditional peace.

Hell, Iwo Jima might have ended even later if the Japanese had not committed to suicide charges a la WWI.
 

ben0628

Banned
Of course, delaying the American Pacific Campaign means the Soviets will be able to conquer more land before the Japanese surrender, which would affect the Cold War greatly.
 

ben0628

Banned
There is also the chance that with more tunnels, supplies, and men, more Japanese soldiers can hide after the island is taken, and when the majority of US forces leave, they could spring from their hideouts and recapture the island.
 

There is an easy way to complete the tunnels. Kuribayashi didn't want to construct any beach defenses at all because they were too vulnerable (which represented completely throwing out the IJA rulebook), but the High Command found out and forced him to build some. These were the only parts destroyed during the pre-landings bombardment. If Kuribayashi's superiors never found out or bureaucratic inertia/some mistake prevented them from telling him to build beach defenses and he was able to put the man hours and materials used to build them into the main tunnels, that could maybe complete the most important one linking Suribachi to the rest of the island.

The rest of this looks pretty unworkable though. It's hard to see how the IJA could be resupplied given that the U.S. had achieved sea supremacy by this point and was sinking everything the Japanese sent to their garrisons. I also question whether Iwo had enough water or shelter for 50,000 men. That might actually be outright counterproductive because it would spread their meager supplies out even further, resulting in everybody being at an even lower state of combat capability. when the landing craft hit the beaches.
 
The rest of this looks pretty unworkable though. It's hard to see how the IJA could be resupplied given that the U.S. had achieved sea supremacy by this point and was sinking everything the Japanese sent to their garrisons. I also question whether Iwo had enough water or shelter for 50,000 men. That might actually be outright counterproductive because it would spread their meager supplies out even further, resulting in everybody being at an even lower state of combat capability. when the landing craft hit the beaches.
We need an earlier POD, so that there are sufficient supplies and provision for water in place without need for resupply before the island was cut off.
 
We need an earlier POD, so that there are sufficient supplies and provision for water in place without need for resupply before the island was cut off.

That's gonna be hard to do. The U.S. had naval superiority for some really insoluble reasons like crushing industrial superiority, bad doctrine and technology on the Japanese side, and them generally sucking at ASW warfare. You'd need a POD going really far back, to the point where the butterflies might very well prevent the Pacific War and the Battle of Iwo Jima as we know it from happening.
 
That's gonna be hard to do. The U.S. had naval superiority for some really insoluble reasons like crushing industrial superiority, bad doctrine and technology on the Japanese side, and them generally sucking at ASW warfare. You'd need a POD going really far back, to the point where the butterflies might very well prevent the Pacific War and the Battle of Iwo Jima as we know it from happening.
How'd the IJA get 26,000 men, artillery, tanks and naval guns to the island? Perhaps 26,000 men is tops, but I don't think we need ASB to get the tunnels finished.
 
Agreed, by the time the IJA needed to reinforce the island USN submarines made that difficult at best. You're going to have trouble shipping any more men or equipment to Iwo at this point in the war...
 
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