What happened IOTL:
A major reason that the Chinese army held onto the besieged city of Shanghai as long as it did, even though it was on the brink of collapse, was that China was hoping for Western intervention in the Sino-Japanese War. Western nations had been paying little attention to China's plight since they were preoccupied with the situation in Europe. In addition, most Western nations had little prospect that their intervention would help China in the long run because they believed that China would eventually lose. If China was deemed militarily weak, economically backward, and politically disunited by Western powers, it would not make sense for them to help China when it seemed bound for defeat by Japan. Thus, Chiang Kai-shek had to devote everything China had to offer to make sure the Western powers knew that the present conflict between China and Japan was a major war, not a collection of inconsequential "incidents" as had been the case previously. Based on this political strategy, Chiang Kai-shek ordered his troops to fight to the death, in an attempt to arouse international sympathy and cause the international community to adopt measures that would help China and sanction Japan.
On September 12, one month after the Battle of Shanghai began, China formally brought the case against Japan to the League of Nations. Again, the League was not able to formulate any effective sanctions against Japan, other than an October 4 statement that gave China "spiritual support". The United States was not a member of the League, and Great Britain and France were reluctant to challenge Japan. But of all the major Western powers, only the United States, since it wasn't embroiled in the volatile European affairs, seemed both capable of confronting Japan and willing to do so. On October 5, President Franklin D. Roosevelt gave the Quarantine Speech, calling for the United States to help nations fight against aggressor nations. This speech had a tremendous effect on raising China's morale, and since America seemed willing to confront Japan, the British representative suggested closing the League case and convening the Nine Power Treaty Conference, scheduling it to begin in early November. Since the Nine-Power Treaty was signed as a result of the Washington Naval Conference of 1922, the opening of the Conference automatically brought the United States into the effort to rein in Japanese aggression.
American entry into the international response brought new hope to the Chinese, and Chiang Kai-shek again reiterated the need for his troops to hold on to Shanghai to prove that China was indeed worth fighting for. But by mid-October, the Chinese situation in Shanghai had become increasingly dire, and the Japanese had made significant gains. The vital town of Dachang fell on October 26, and the Chinese were forced to withdraw from metropolitan Shanghai. But with the Nine Power Treaty Conference about to begin, Chiang Kai-shek ordered his troops to stay in the Shanghai battlefield, instead of retreating to the Wufu and Xicheng Lines to protect Nanjing, and also left one lone battalion to defend the Sihang Warehouse in metropolitan Shanghai. Because Shanghai was the most important Chinese city in Western eyes, the troops had to fight and hold on to the city as long as possible, rather than moving toward the defense lines along nameless towns en route to Nanjing. And on November 3, the Conference finally convened in Brussels- with Japan refusing to participate in the Conference, maintaining that its dispute with China was outside the purview of the Nine-Power Treaty.
While the Western powers were in session to mediate the situation, the Chinese troops were making their final stand in Shanghai and had all hopes for a Western intervention that would save China from collapse. However, the Conference dragged on with little progress; President Roosevelt and Secretary Hull had gave instructions to Norman H. Davis, the U.S. delegate to the conference, stating that the first objective of the foreign policy of the United States was national security, and that consequently the U.S. sought to keep peace and promote the maintenance of peace; that the USA as a signatory to the Kellogg-Briand Pact had renounced war as an instrument of national policy; and that "public opinion in the United States has expressed its emphatic determination that the United States keep out of war". Mr. Davis was instructed to keep in mind the interest of the United States in peace in the Pacific and in the Far East, as evidenced by the Washington Naval Conference, the statements relating to foreign policy made by the President in his Chicago address of October 5, and this Government's statement of October 6 on the controversy between China and Japan. In the view of the US Government the primary function of the Conference was "to provide a forum for constructive discussion, to formulate and suggest possible bases of settlement, and to endeavor to bring the parties together through peaceful negotiation".
However, it was also emphasized to Davis that, if the U.S. were to avoid an ultimate serious clash with Japan, some practical means must be found to check Japanese conquest, and to make effective the collective will of the powers which desired the settlement of international controversies by peaceful means; that the Conference might be an agency for bringing to bear upon Japan every moral pressure directed toward bringing about a change in Japanese attitude and policy. Finally, Davis was instructed to "observe closely the trend of public opinion in the United States and take full account thereof." On November 15, the Conference adopted a declaration affirming that the representatives of 15 states considered the conflict between China and Japan to be of concern to all countries parties to the Nine-Power Treaty and the Kellogg-Briand Pact. In the presence of this difference between the views of the Conference and the Japanese Government, the Conference considered that there was no opportunity at the time for carrying out its terms of reference so far as they related to bringing about peace by agreement. And on November 24 1937, the Nine-Power Treaty Conference convened for the last time and then adjourned indefinitely, without producing any measures that would stop Japanese aggression.
At this point, the Washington System had completely collapsed. In its final declaration, the Conference stated that it strongly reaffirmed the principles of the Nine-Power Treaty; that it believed that a satisfactory settlement between China and Japan could not be achieved by direct negotiation between the parties to the conflict alone and that an acceptable agreement could be achieved only by consultation with other powers principally concerned; that it strongly urged that hostilities be suspended and resort be had to peaceful processes; that the Conference deemed it advisable temporarily to suspend its sittings; that the conflict remained, however, a matter of concern to all the powers assembled at Brussels; and that the Conference would be called together again when it was considered that deliberations could be advantageously resumed (i.e, never). The United States delegate reported at the conclusion of the Conference that it had demonstrated the "unwillingness of Japan to resort to methods of conciliation" and that the Japanese continued to insist that the issues between Japan and China were exclusive to those two countries; whereas the Conference powers, with the exception of Italy, affirmed that the situation was of concern to all members of the family of nations. And with all hope having been lost, Shanghai was finally abandoned by KMT China, with the weakened Wufu and Xicheng defense lines greatly contributing towards the subsequent Japanese 'Rape of Nanjing'.
What happens instead ITTL:
After President Franklin D. Roosevelt gives the Quarantine Speech on October 5th 1937, calling for the United States to help nations fight against aggressor nations, the British representative's suggestion of closing the League case and convening the Nine Power Treaty Conference is never taken up ITTL, with the European Great Powers far too preoccupied by goings-on in Europe. And though the option of convening the Nine Power Treaty Conference as "an agency for bringing to bear upon Japan every moral pressure directed toward bringing about a change in Japanese attitude and policy" having been closed off to the Americans, Roosevelt still decides to act upon his sentiment that "some practical means must be found to check Japanese conquest"; electing to impose harsher sanctions against the Japanese, and resort to providing loan assistance for war supply contracts to the Chinese. And President Roosevelt also reluctantly accepts the suggestions of the Commander of the US Asiatic Fleet, Admiral Yarnell (who'd already made Shanghai his base of operation on 13 August 1937, residing aboard the presidential flagship USS Augusta after having moored it in a prominent position off the Shanghai Bund, with the flagship's Marine Detachment having been sent ashore to aid the 4th Marines in establishing defensive positions to keep hostilities out of the neutral enclaves), to dispatch a division of heavy cruisers to carry out the evacuation.
Rather than "bringing about a change in Japanese attitude and policy", "to keep peace and promote the maintenance of peace", however, these moves by the USA greatly anger and enrage the Japanese military, whilst greatly boosting the morale and hopes of the Chinese. And the situation escalates far more rapidly, before those heavy cruisers can arrive. IOTL, tensions and aggressions only escalated to the point where Japanese naval planes sank the US gunboat Panay and three Standard Oil tankers in the Yangtze River north of Nanking on 12 December 1937, in the USS Panay Incident, long after the Battle of Shanghai and international arbitration regarding the Second Sino-Japanese War had come to an end (with US Navy cryptographers having intercepted and decrypted traffic relating to the attacking planes which clearly indicated that they were under orders during the attack, and that it had been intentional; though this information was kept classified at the time, knowing that public knowledge of this would propel the US into war against Japan in the same manner that the sinking of the USS Maine had against Spain, with the Japanese government's formal apology and offer of indemnity to settle the incident being accepted by the US in April 1938).
But ITTL, those same renegade factions within the Japanese military who wanted to force the U.S. into an active conflict so that the Japanese could once and for all drive the U.S. out of China, and who gave the order to sink the USS Panay IOTL, are further strengthened, emboldened and galvanized by the 'increased provocation' of America's perceived support of KMT China, to the extent where they instead give the orders to attack vessels of the Yangtze River Patrol present in the region in early November. In the ensuing attacks by Japanese naval planes, while the USS Augusta is left largely unmolested for the time being, not only the USS Panay, but the USS Oahu, USS Tutuila and USS Luzon as well, are all bombed and strafed on the same day, with two of these being sunk. And with the American public already agitated over reported Japanese atrocities, word of these attacks against the Yangtze Patrol by the IJN, with the Battle of Shanghai still ongoing, are met with disbelief and sheer outrage in the USA.
With US public opinion swinging to be overwhelmingly in favor of war against Japan in the aftermath, there's more than enough catalyst for Roosevelt's administration to take this consensus into account; and whilst the Japanese still attempt to apologize, protesting that their attacks had been unintentional and that their pilots never saw any American flags on the vessels they'd attacked, as they claimed (equally falsely) IOTL, their efforts to mollify the Americans fall on increasingly deaf ears. International relations between the USA and Japan continue to rapidly deteriorate beyond the point of no return, and tensions continue to ramp up, with the USA severing diplomatic ties with Japan; before the USA ultimately declares war against Japan, before 1937 comes to an end.
*****
So then, in this scenario, how do you reckon such a conflict'd go? How invested do you think either Japan or the USA'd be in this conflict, and what terms of victory, or defeat might they be willing to accept to bring it to an end? Might any other nations be inclined to join in, on either Japan's or the USA's side (and how many- enough to snowball into TTL's version of WW2)? And how massive an impact could this wind up having; how much do you reckon that the course of WW2 and world history might diverge from OTL?
A major reason that the Chinese army held onto the besieged city of Shanghai as long as it did, even though it was on the brink of collapse, was that China was hoping for Western intervention in the Sino-Japanese War. Western nations had been paying little attention to China's plight since they were preoccupied with the situation in Europe. In addition, most Western nations had little prospect that their intervention would help China in the long run because they believed that China would eventually lose. If China was deemed militarily weak, economically backward, and politically disunited by Western powers, it would not make sense for them to help China when it seemed bound for defeat by Japan. Thus, Chiang Kai-shek had to devote everything China had to offer to make sure the Western powers knew that the present conflict between China and Japan was a major war, not a collection of inconsequential "incidents" as had been the case previously. Based on this political strategy, Chiang Kai-shek ordered his troops to fight to the death, in an attempt to arouse international sympathy and cause the international community to adopt measures that would help China and sanction Japan.
On September 12, one month after the Battle of Shanghai began, China formally brought the case against Japan to the League of Nations. Again, the League was not able to formulate any effective sanctions against Japan, other than an October 4 statement that gave China "spiritual support". The United States was not a member of the League, and Great Britain and France were reluctant to challenge Japan. But of all the major Western powers, only the United States, since it wasn't embroiled in the volatile European affairs, seemed both capable of confronting Japan and willing to do so. On October 5, President Franklin D. Roosevelt gave the Quarantine Speech, calling for the United States to help nations fight against aggressor nations. This speech had a tremendous effect on raising China's morale, and since America seemed willing to confront Japan, the British representative suggested closing the League case and convening the Nine Power Treaty Conference, scheduling it to begin in early November. Since the Nine-Power Treaty was signed as a result of the Washington Naval Conference of 1922, the opening of the Conference automatically brought the United States into the effort to rein in Japanese aggression.
American entry into the international response brought new hope to the Chinese, and Chiang Kai-shek again reiterated the need for his troops to hold on to Shanghai to prove that China was indeed worth fighting for. But by mid-October, the Chinese situation in Shanghai had become increasingly dire, and the Japanese had made significant gains. The vital town of Dachang fell on October 26, and the Chinese were forced to withdraw from metropolitan Shanghai. But with the Nine Power Treaty Conference about to begin, Chiang Kai-shek ordered his troops to stay in the Shanghai battlefield, instead of retreating to the Wufu and Xicheng Lines to protect Nanjing, and also left one lone battalion to defend the Sihang Warehouse in metropolitan Shanghai. Because Shanghai was the most important Chinese city in Western eyes, the troops had to fight and hold on to the city as long as possible, rather than moving toward the defense lines along nameless towns en route to Nanjing. And on November 3, the Conference finally convened in Brussels- with Japan refusing to participate in the Conference, maintaining that its dispute with China was outside the purview of the Nine-Power Treaty.
While the Western powers were in session to mediate the situation, the Chinese troops were making their final stand in Shanghai and had all hopes for a Western intervention that would save China from collapse. However, the Conference dragged on with little progress; President Roosevelt and Secretary Hull had gave instructions to Norman H. Davis, the U.S. delegate to the conference, stating that the first objective of the foreign policy of the United States was national security, and that consequently the U.S. sought to keep peace and promote the maintenance of peace; that the USA as a signatory to the Kellogg-Briand Pact had renounced war as an instrument of national policy; and that "public opinion in the United States has expressed its emphatic determination that the United States keep out of war". Mr. Davis was instructed to keep in mind the interest of the United States in peace in the Pacific and in the Far East, as evidenced by the Washington Naval Conference, the statements relating to foreign policy made by the President in his Chicago address of October 5, and this Government's statement of October 6 on the controversy between China and Japan. In the view of the US Government the primary function of the Conference was "to provide a forum for constructive discussion, to formulate and suggest possible bases of settlement, and to endeavor to bring the parties together through peaceful negotiation".
However, it was also emphasized to Davis that, if the U.S. were to avoid an ultimate serious clash with Japan, some practical means must be found to check Japanese conquest, and to make effective the collective will of the powers which desired the settlement of international controversies by peaceful means; that the Conference might be an agency for bringing to bear upon Japan every moral pressure directed toward bringing about a change in Japanese attitude and policy. Finally, Davis was instructed to "observe closely the trend of public opinion in the United States and take full account thereof." On November 15, the Conference adopted a declaration affirming that the representatives of 15 states considered the conflict between China and Japan to be of concern to all countries parties to the Nine-Power Treaty and the Kellogg-Briand Pact. In the presence of this difference between the views of the Conference and the Japanese Government, the Conference considered that there was no opportunity at the time for carrying out its terms of reference so far as they related to bringing about peace by agreement. And on November 24 1937, the Nine-Power Treaty Conference convened for the last time and then adjourned indefinitely, without producing any measures that would stop Japanese aggression.
At this point, the Washington System had completely collapsed. In its final declaration, the Conference stated that it strongly reaffirmed the principles of the Nine-Power Treaty; that it believed that a satisfactory settlement between China and Japan could not be achieved by direct negotiation between the parties to the conflict alone and that an acceptable agreement could be achieved only by consultation with other powers principally concerned; that it strongly urged that hostilities be suspended and resort be had to peaceful processes; that the Conference deemed it advisable temporarily to suspend its sittings; that the conflict remained, however, a matter of concern to all the powers assembled at Brussels; and that the Conference would be called together again when it was considered that deliberations could be advantageously resumed (i.e, never). The United States delegate reported at the conclusion of the Conference that it had demonstrated the "unwillingness of Japan to resort to methods of conciliation" and that the Japanese continued to insist that the issues between Japan and China were exclusive to those two countries; whereas the Conference powers, with the exception of Italy, affirmed that the situation was of concern to all members of the family of nations. And with all hope having been lost, Shanghai was finally abandoned by KMT China, with the weakened Wufu and Xicheng defense lines greatly contributing towards the subsequent Japanese 'Rape of Nanjing'.
What happens instead ITTL:
After President Franklin D. Roosevelt gives the Quarantine Speech on October 5th 1937, calling for the United States to help nations fight against aggressor nations, the British representative's suggestion of closing the League case and convening the Nine Power Treaty Conference is never taken up ITTL, with the European Great Powers far too preoccupied by goings-on in Europe. And though the option of convening the Nine Power Treaty Conference as "an agency for bringing to bear upon Japan every moral pressure directed toward bringing about a change in Japanese attitude and policy" having been closed off to the Americans, Roosevelt still decides to act upon his sentiment that "some practical means must be found to check Japanese conquest"; electing to impose harsher sanctions against the Japanese, and resort to providing loan assistance for war supply contracts to the Chinese. And President Roosevelt also reluctantly accepts the suggestions of the Commander of the US Asiatic Fleet, Admiral Yarnell (who'd already made Shanghai his base of operation on 13 August 1937, residing aboard the presidential flagship USS Augusta after having moored it in a prominent position off the Shanghai Bund, with the flagship's Marine Detachment having been sent ashore to aid the 4th Marines in establishing defensive positions to keep hostilities out of the neutral enclaves), to dispatch a division of heavy cruisers to carry out the evacuation.
Rather than "bringing about a change in Japanese attitude and policy", "to keep peace and promote the maintenance of peace", however, these moves by the USA greatly anger and enrage the Japanese military, whilst greatly boosting the morale and hopes of the Chinese. And the situation escalates far more rapidly, before those heavy cruisers can arrive. IOTL, tensions and aggressions only escalated to the point where Japanese naval planes sank the US gunboat Panay and three Standard Oil tankers in the Yangtze River north of Nanking on 12 December 1937, in the USS Panay Incident, long after the Battle of Shanghai and international arbitration regarding the Second Sino-Japanese War had come to an end (with US Navy cryptographers having intercepted and decrypted traffic relating to the attacking planes which clearly indicated that they were under orders during the attack, and that it had been intentional; though this information was kept classified at the time, knowing that public knowledge of this would propel the US into war against Japan in the same manner that the sinking of the USS Maine had against Spain, with the Japanese government's formal apology and offer of indemnity to settle the incident being accepted by the US in April 1938).
But ITTL, those same renegade factions within the Japanese military who wanted to force the U.S. into an active conflict so that the Japanese could once and for all drive the U.S. out of China, and who gave the order to sink the USS Panay IOTL, are further strengthened, emboldened and galvanized by the 'increased provocation' of America's perceived support of KMT China, to the extent where they instead give the orders to attack vessels of the Yangtze River Patrol present in the region in early November. In the ensuing attacks by Japanese naval planes, while the USS Augusta is left largely unmolested for the time being, not only the USS Panay, but the USS Oahu, USS Tutuila and USS Luzon as well, are all bombed and strafed on the same day, with two of these being sunk. And with the American public already agitated over reported Japanese atrocities, word of these attacks against the Yangtze Patrol by the IJN, with the Battle of Shanghai still ongoing, are met with disbelief and sheer outrage in the USA.
With US public opinion swinging to be overwhelmingly in favor of war against Japan in the aftermath, there's more than enough catalyst for Roosevelt's administration to take this consensus into account; and whilst the Japanese still attempt to apologize, protesting that their attacks had been unintentional and that their pilots never saw any American flags on the vessels they'd attacked, as they claimed (equally falsely) IOTL, their efforts to mollify the Americans fall on increasingly deaf ears. International relations between the USA and Japan continue to rapidly deteriorate beyond the point of no return, and tensions continue to ramp up, with the USA severing diplomatic ties with Japan; before the USA ultimately declares war against Japan, before 1937 comes to an end.
*****
So then, in this scenario, how do you reckon such a conflict'd go? How invested do you think either Japan or the USA'd be in this conflict, and what terms of victory, or defeat might they be willing to accept to bring it to an end? Might any other nations be inclined to join in, on either Japan's or the USA's side (and how many- enough to snowball into TTL's version of WW2)? And how massive an impact could this wind up having; how much do you reckon that the course of WW2 and world history might diverge from OTL?