That was the biggest thing, but they were also upset that they didn't get all of the former German provinces in the North Pacific which they wanted.
By "North Pacific" you mean Manchuria? Because there isn't a whole lot of anything else up there outside of North America and Russia. But yeah, there was much in the
Central Pacific that they may have wanted and didn't get.
If they had sent a sizable number of troops to the Western Front and they'd fought (and died) alongside British/French troops, it might have increased their chances of getting the racial equality clause (though British Australia and India were against it).
The various empires of Europe needed the Myth of the Invincible White Man to maintain control over their native populations. The sight of
independently equipped, trained, and led first class armies there were members of the colored peoples (1) of the world would have been a socially shattering event in Asia, Africa, the Ottoman Empire, and even Western Europe. (2)
The sight of Japanese troops in France slaughtering attacking German troops at Verdun, at great cost to themselves, could have particularly explosive consequences should Yellow Peril hysteria reach France. Imagine wounded Imperial Japanese officers coming back from the Western Front being denied entrance into the Cafe de la Paix!




The Japanese people took such effrontery VERY seriously. I can't imagine a worse case of culture clash than this.
1) Sorry for the use of the antiquated term "colored people", but that was the most POLITE term in use at the time.
2) As it was OTL during the Fall of Singapore. And the Japanese went to great lengths to rub it in by humiliating the British, Canadian, and ANZAC troops that surrendered there, and in Burma, Malaya, and Hong Kong.
The Japanese also felt snubbed in the Washington Naval Treaty of 1922, where the set ratio of ships was UK 5: US 5: Japan 3
That was actually not snubbing. As the UK (Atlantic/Indian/Mediterranean) and US (Atlantic/Pacific) were both Two (Two and a half, really) Ocean Powers they needed bigger navies. The reward Japan got for having a fleet 60% that of either of the Anglo Powers was in the agreement by Britain and the US that no British or American bases in the Pacific would be fortified. The exceptions being Singapore (half a fortress), Corregidor, Oahu, the Panama Canal, and the US West Coast. Japan was specifically allowed to fortify their bases wherever and however much they might like to.
Which explains why and how the Japanese had such an easy time overrunning so much of the Pacific in 1941-42, while the Americans and Australians had to fight for every inch of heavily defended Japanese soil in the long slog back.
Besides, the Japanese cheated like sons of bitches in terms of honoring their treaty tonnage limits. And to a degree that would have made the Soviets drool.

That's why 10 of the USN's 18 heavy cruisers (CA's) at the start of WWII were sunk in battle by war's end. They had the range, speed, gunnery, and size of their opposing IJN CA's, but they were over-sized destroyers compared to their heavily armored Japanese counterparts. And Japan had the most powerful torpedoes in the world. By war's end, most of the old "treaty cruisers" had been sent to the North Pacific out of harm's way, like the old and fragile CV Ranger was kept in the Atlantic.
When they WERE put in harm's way, you got Savo Island and the sinking of the Indianapolis.
True, it's CERTAINLY far easier. However, they're likely to get far less "credit" there, even if they're fighting along Brits, Anzacs, etc and they do as much fighting an dying.
Agreed. Not only the normal level of nationalism causing people to blow their own nation's contributions out of proportion, while belittling (or ignoring) the role of others; But also the racial component as well. I doubt seriously that newspapers in the wide flung Empires would scarcely even mention the Japanese.
Now, if they were able/willing to get involved early enough, perhaps they could have sent a sizable force to Gallipoli and actually taken it. The Anzacs were amazingly brave, but their leadership (especially on day 1 ashore) was horribly inconsistent, with some leaders simply stopping, even though their objectives were wide open in front of them.
The command of the British troops was hardly any better, if not in fact even worse. Command
elan was not to be seen.
The Japanese would have had to DoW the Central Powers on a Pearl Harbor level of mobilization to be able to sortie a sizable force and get them all the way to Gallipoli IMHO.
The Japanese DID have some good experience with combine Ground-Naval assaults from the Russo-Japanese War.
Agreed
If they were the "saviors of Gallipoli", they'd get some serious street cred from that.
I doubt it.

More likely they'd be treated in Anglo-French newspapers (with the approval of their governments) as little more than Imperial Native troops under the command of their White Betters.

With every opportunity to suggest that Japanese troops were under the command of Japanese-speaking British officers!
Silly? Lawrence of Arabia to the
Nth degree.
The dying bit would not make that much difference. The Chinese did that then got well screwed at Versailles.
I doubt it would be politically possible for even the Imperial Japanese Army to get away with sending a million sons into the trenches of France, never to return. And if they did, and weren't given the whole of China and two-thirds of the Pacific Ocean as a Japanese Protectorate (never mind equal footing on naval disarmament), then World War Two starts at Versailles
Political impact aside, might this have reduced the cultural fear of "The Yellow Peril" that was so prevalent at the time? If Englishmen (and the men of the Dominions), Frenchmen, and Americans had fought side-by-side with Japanese troops in the trenches of France and Flanders, could it have altered public perceptions in any significant way?
Did 180,000 African-Americans fighting in Federal uniform do anything for race relations beyond the 13th, 14th, and 15th Amendments? Were feelings significantly changed? When the White troops of the Union Army went home, by and large when they took off their uniforms they put their old beliefs about race back on.
The Japanese troops might have impressed the locals with their courage and personal sense of honor. But I kind of doubt they'd want to see their daughters bringing any of them home with them.



