After 1938 the nature of the Sino-Japanese war changed from offensive to defensive. The dramatic battles of the first year of the war were fewer in number. Instead, China's fate became tied up with shifting alliances, diplomatic intrigues and social change that would permanently alter the country's course. Central to those changes were new ideas of social provision: the circumstances of war forced the new regimes into competition with each other. Nationalists and Communists would strive to demonstrate that as the state demanded more of its people, so they should demand more of their government.
Many aspects of life in the city of Chongqing were beyond the Nationalist government's control, and none more so than the terrifying new reality of constant bombings. In the winter of 1938 there were a few 'trial raids' on the city. The attacks began in earnest from the spring of 1939, and it was the destruction that rained down on the twentieth anniversary of the nationalist Fourth of May demonstrations which marked the start of a stream of destruction from the sky that would be part of everyday existence for years to come.
The Japanese were almost as unprepared for the responsibilities of occupation as the Nationalists were for governing in retreat. The invaders had not expected the events of July 1937 to turn into an all-out war, and they had few concrete plans in place to deal with the extent of their sudden new conquests. Their general technique was to find collaborators, preferably people of some standing, to run local government for them. They wanted their conquests to pay for themselves, or better still, to provide revenue for Japan, but realized that in the short term they would have to spend money to restore order.
The war changed the fortunes of the Chinese Communist Party. No longer a band of rebels on the run, they were now officially regarded as a junior partner in the United Front against Japan. The development of Communist political policy in the years of the war was inexorably shaped by the demands of warfare itself. The war also transformed the career of Mao Zedong. Mao had not been the only possible leader for the party when the war broke out, but his position had been greatly strengthened.
The Communists also advanced in central China, setting up the JinChaJi base in the borderlands between Shanxi and Hebei, as well as in northwest Shanxi and the Taihang mountains of southeast Shanxi. The initial years of the war saw significant expansion of the Communist Party and its allied forces. Between 1937 and 1941 the number of members rose from some 40,000 to 763,447, and from a total force of some 92,000 at the start to some 440,000 troops over the same period.
After the fall of Wuhan, Chiang Kai-shek had made it clear that the government had no intention of surrender. He also believed that Wuhan, which had been defended at the cost of so much blood, was no longer essential to his strategy. New routes to supply Free China from the northwest and northeast were being established, and the Nationalists were now defending several crucial lines. But there was still no likelihood of significant international intervention in China. The CCP continued to maintain control in parts of northern and central China, but the Nationalists knew that they would be forced to rely on their own resources to avoid defeat. The first stage of the war was over. Now it was time for the second, defensive stage, to begin.
From 1939 to 1941 the conflict had become not only a war of resistance against Japan and its Chinese collaborators, but also a duel between the Nationalists and the Communists. Chiang ordered new political and economic measures against Mao's heartland. In particular, he sought to regain control of parts of Hebei, Shanxi, Henan and Shandong that the CCP had come to think of as its own areas of control. The campaign aimed to box the Communists in, rather than to invade their territory, but it was a clear sign that relations between the two sides were beginning to break down. However, neither side could afford to let its own public, let alone the international community, think that the United Front had failed.
During their march to Wuhan, the Japanese had bypassed Nanchang, the capital of Jiangxi Province, as they had encountered strong resistance there. The city, on the western shore of Lake Poyang, dominated the fertile plains of north Jiangxi and was a base for the 9th War Zone under Xue Yue. Located along the south shore of the Yangtze River, the 9th War Zone was a major threat to the Japanese. The battle for Nanchang took place in the spring of 1939. The Japanese took the city.
Chiang's troubles were made even worse by events in Europe. In the late summer of 1939 two events changed the face of the conflict: the expected outbreak of war between Germany and Britain along with France, and the unexpected outbreak of peace between Germany and its ideological foe, the USSR. At a stroke, the attention of the European powers was concentrated on their own fight for survival. The war in East Asia, already a secondary concern for them, now became a minor matter indeed. The Japanese also exploited the weakness of China's potential European allies by effectively cutting off the supply lines China received from Burma and Indochina.
The Japanese Imperial Army, its operations now unified under the China Expeditionary Command, sent 100,000 troops to take the central Chinese city of Changsha. The city had already suffered grievously after the retreat from Wuhan when Chiang had ordered that it be burned. If the Japanese could capture Changsha, then they would hold Hunan, one of the great breadbasket provinces of central China. From there, the way to Sichuan in the west would lie open, and they could hope to defeat Chiang's regime in Chongqing once and for all. But the Japanese assault on Changsha failed.
The Nationalist military now seized the initiative with a series of offensives across the whole country. In a series of coordinated attacks, the army was to strike out and recapture huge swathes of territory, from Yan Xishan's former area of control in Shanxi province in north central China to Guangxi in the southwest. But almost nothing went according to plan. Yan Xishan carved out his own deal with the Japanese for control of parts of Shanxi and withdrew from the campaign. In the south, the Japanese surprised Chiang by launching an invasion of the southwestern province of Guangxi, capturing the city of Nanning and cutting off the route to the sea.
After the Winter Offensive, in the remainder of 1940 the Nationalists did not launch another major operation against the Japanese. This was the result in part of a further deterioration in the international situation. In July 1940, Britain agreed to stop the supply of arms, ammunition, petrol, trucks, and railroad building materials through Burma and Hong Kong. Domestically, the second half of the year was dominated by further conflict between the Communists and the Nationalists.
China's situation was precarious by the spring of 1940. High-level Japanese negotiators tried to secure an agreement with Chiang in Chongqing, while Wang Jingwei was attempting to formalize his own Nationalist government in Nanjing. This strategy, known in Chinese as the Tong Operation, and in Japanese as Operation Kiri, led to talks in Hong Kong. The talks foundered on issues of principle: Japan wanted to station troops in northern China and gain formal recognition of Manchukuo, which Chiang absolutely refused.
Things worsened in the spring of 1940: the city of Yichang in Hubei province fell to a new Japanese advance. Yichang had been the transit point from Sichuan to the other parts of the country, and its loss meant that Chiang's regime was even more isolated. As had happened before, an initially successful Nationalist assault had turned into a disaster.
If previously the Japanese air force had been used tactically in support of infantry operations, it now began a strategic bombing campaign against the Chinese rear. The introduction of the famous Zero fighter with its longer range made this possible. The first fifteen were deployed in China in the summer of 1940 and the airplane demonstrated its value when in August 1940 it shot down all Chinese airplanes defending Chongqing, thus making it possible for Japanese bombers to attack unopposed. During the long summer of 1940, cities such as Chongqing, Chengdu, Xi’an, Changsha, and Lanzhou were subjected to virtually continuous Japanese air assault.
By the summer of 1940 the two major Communist armies dominated much of north and central China. The Eighth Route Army under the command of Peng Dehuai launched the only major conventional military offensive by a Communist army during the War: they launched an all-out assault on railway lines, roads, bridges and other elements of the infrastructure necessary for Japanese control in north China. The fighting invited a massive Japanese counter-assault that enabled them to reassert control of railway lines.
The disastrous year of 1940 seemed to cast doubt on the idea that there might be any future for China outside the Japanese Empire. Nonetheless, events far away would provide a sliver of hope for the National Government. Late in 1940, Franklin D. Roosevelt had been re-elected as president of the United States. Roosevelt and his Secretary of State, Cordell Hull, were both aware that the Nazi domination of Europe had laid down a profound challenge to American influence there. And with China's 'Open Door' to trade closed off under Japanese occupation, it was becoming clear that simple neutrality might no longer be an option.
For the Battle of Southern Henan the Japanese mobilized 150,000 troops, 300 tanks, and 100 airplanes. Besides securing the southern section of the Beiping-Hankou Railroad, the Japanese sought to weaken the 5th War Zone, which continued to be a threat after the Yichang Campaign. Instead of Chinese forces becoming encircled, it was the Japanese who were surrounded. The battle ended with the Japanese, minus their casualties, back at their jumping off points.
The Battle of Shanggao in Jiangxi lasted about a month. This Japanese offensive came in response to the re-training and re-arming program of the 9th War Zone. Lo Zhoying’s Group Army in this war zone remained a major threat to Japanese positions in Hunan and Jiangxi as well as the Yangtze River. Shanggao was a city of considerable strategic significance. The battle was a Chinese victory that is not as well known as the Battle of Taierzhuang but which was at least as impressive, especially given the disasters that had befallen the Nationalists in 1940.
The victory at Shanggao was soon overshadowed by the defeat of the 1st War Zone under Wei Lihuang in the Zhongxiao mountains of Southern Shanxi. In this campaign, the Japanese were able to achieve their objectives and to firm up supply lines. This made it possible for the Japanese to cut through Nationalist positions, isolate various Chinese forces, and then destroy them. The Nationalists were forced to retreat from the Zhongxiao Mountains.
The world woke up to the news that some three million German troops were on the move into the Soviet Union. Operation Barbarossa, Hitler's invasion of the USSR, was a stunning reversal of the previous two years of non-aggression between the two major European dictatorships. In Chongqing and Yan'an the German attack on the USSR was seen as a positive sign that the war might be turning against Japan. In Nanjing it was seen differently. Zhou Fohai guessed that the Japanese could not reconcile their treaty of neutrality with the USSR and their membership of the Anti-Comintern Pact, which was supposed to bind the Axis powers together against Soviet expansionism. However, because the Germans had attacked first, Zhou noted, Japan was not obliged to assist them.
The final Japanese operation of 1941 was a second attempt to conquer Changsha. Rather than seeking to encircle Changsha, the Japanese attempted to take the city by a quick offensive, including by deploying airborne assault forces. Chinese tactics relied on a gradual withdrawal at the front, attacks in the rear, and in this case large-scale attacks on the eastern flank of the Japanese. Once the Japanese reached the outskirts of Changsha, the Chinese were able to cut their supply lines, and counterattacked. As at Shanggao, the Japanese lost nearly half of their forces without making substantial gains.
The summer of 1941 marked a decisive shift in the geopolitics of the war. Germany's invasion of Russia now confronted Japan with the choice of whether or not to enter the war against the USSR as well. Having dismissed the idea of attacking the USSR, Japan's leaders turned their attention instead to another great power: the United States. The inability of the Japanese to achieve further traction in China led to calls for a wider expansion of their influence in the region, in particular Southeast Asia with its rich supply of oil, rubber and other materials that were vital to the war effort. The Roosevelt administration was increasingly concerned by these developments. Now the administration increased the amount of aid available to China.
In the early morning of 7 December 1941, the US Pacific Fleet was anchored at Pearl Harbor in Hawaii. Two waves of Japanese bomber aircraft, launched from six aircraft carriers, attacked the vessels and their sleeping crews, destroying the battleship Arizona outright and damaging seventeen others, as well as most of the military aircraft parked nearby. Some 2,400 Americans died, and another 1,100 were wounded. Chiang Kai-shek heard the news at one o'clock in the morning and immediately dictated a letter of support to President Roosevelt, pledging commitment to a new 'common battle'.