In WWII, the US had two paths to mainland Japan. The Army's involved going through Papua New Guinea and the Philippines, while the Navy's involved "island hopping." The US had enough resources to execute both plans, but do historians have an opinion as to which was better?

by ottolouis

In WWII, General MacArthur proposed a plan of invading Japan first by starting in Australia, taking Papua New Guinea, and then taking the Philippines. Taking the Philippines allowed the US to cut Japan off from its oil in Indonesia, and allowed it to serve as a larger staging ground for a future attack on the Japanese mainland. However, Admiral Nimitz wanted the US to gradually take islands in the Western Pacific, and build airfields that would facilitate the taking of more islands. Eventually, the US would take the Japanese mainland this way. This latter strategy is much more iconic, involved the United States Marine Corps, and resulted in famous battles like Saipan, Tarawa, Iwo Jima, Okinawa, etc. In the end, the US had sufficient resources to execute both plans. However, do military historians today have a general opinion as to which strategy was better? My intuition is that the Army's strategy was better because it threatened Japanese logistics more (the US was able to interdict Japanese shipping from Indonesia) and also served as a larger base for an invasion of Japan. What do most historians think?

perat0

As no one else has tried to answer this yet, I'll give it a go.

US didn't really need the Philippines nor the Indonesian archipelago to threaten supply lines. Submarines from western Australia and from islands in mid Pacific could do it just fine. After the capture of Marianas(Guam, Saipan) and Ulithi, even Carrier task forces could "roam free" in West Pacific which was shown in the Formosa Air Battle / Battle of Taiwan Sea. So land based aircraft and closer naval bases weren't necessary for strangling the Japanese supply from Indonesian and Malayan oil fields, it was already struggling in 1943 and very much at the end of it's tether in 1944 before the Philippines was taken. Same rule applies to capturing Philippines for a forward base. It wasn't necessary in 1944 or 1945 it served as resource sink rather although it also served as a resource sink for Japanese as well.

Although I haven't come up with anyone today actually seriously promoting the southern strategy as a superior one, there were multiple reasons why it was on the table and was performed during the war.

  1. As you mentioned, they had the resources to pull it off. This wasn't the case in 1942 but back then they were practically fighting "in the same area" close to Australia when Army was fighting in New Guinea and Navy in Guadalcanal. The paths really diverged only in 1943 when Navy started it's island hopping from Gilberts and to Marshalls early 1944.
  2. Army vs Navy. There was a serious friction between the two armed forces and lot of it had to do with personalities down in South Pacific. Both vied for resources and both tried to get their plans and commanders ahead of the other. This goes all the way to the top where Marshall and Arnold were the Army's top dogs and King was navy. King was constantly demanding more resources to Pacific while Marshall and Arnold were looking more to Europe per US promises to go Germany first.
  3. US domestic politics, although for a minor part. For this I cannot give any good answer but for my understanding Republicans(their newspapers at least) backed MacArthur and saw the navy as their opponent. They were critical of navy's operations in mid Pacific and held MacArthur as their own. I do not know why this was so. He was later thought as a possible Republican candidate for presidency, but I do not know why the political division was such and was it only between Roosevelt being democrat or was there a bigger division in US politics between navy and army.
  4. MacArthur and Philippines. There was a lot of politics in this too, but more in the territory of Foreign politics. Commonwealth of the Philippines was considered under US protection and because Japanese had invaded, there existed a pressure the capture it back and free the people of Philippines. MacArthur was a major player in to Philippines, being the Military advisor of Philippines from 1935-42 and held himself responsible for Philippines. Also there were considerations if USA should go for mainland China before trying to get to Japan. This all had to do with USA's interests in China before(and during) the war but also for getting better airbases.
  5. Resources were scant in 1942. Although the US resources were seemingly infinite in 1944, they weren't that in 1942. Only a couple of CV:s, less than ten tankers available and little experience on the fly refueling, no proper forward bases, very little amount of proper landing craft. Also at that point land based aircraft were seen to have the major upper hand hindering any carrier assault on mutually supporting airfields. What this meant that in 1942 the mid Pacific route seemed a lot more intimidating than the one from through the Islands of New Guinea and Indonesia where USAAF could support the forces a lot better. The CTFs of 1944 and 1945 could simply overwhelm the land based aircraft of multiple airfields, a feat that seemed impossible to most admirals in 1942.