Among Song Ziwen's 4 resignations, the reasons behind it are intriguing
Song Ziwen served as finance minister of the Nanjing government in early 1928 and finally resigned in October 1933, a six-year period. In the Nanjing government, he was the longest-serving finance minister besides Kong Xiangxi. However, in these 6 years, Song Ziwen's finance minister is not consistent, and there have been 4 resignations in the middle, either true or false, long or short, for different reasons, quite intriguing.

Song Ziwen first offered his resignation on August 6, 1929. On August 1, 1929, kuomintang military and political leaders held the second dispatch meeting in Nanjing. Before the meeting, it was planned to reduce the army to 600,000 people, but at the meeting it was increased to 800,000 people, in fact, none of the factions of Jiang, Feng, and Yan refused to reduce their own troops.
Under these circumstances, Song Ziwen resigned from the Nanjing government on the grounds that military expenditure could not be reduced after the dispatch meeting, the budget could not be implemented, and the financial difficulties could not be dealt with. Song Ziwen had raised a lot of military funds for the Nanjing government, so his resignation was not agreed by the government, and on August 7, Chiang Kai-shek arrived in Shanghai to retain Song Ziwen. On the 9th, the Nanjing government ordered the retention of song. Song Ziwen originally did not really resign, but only wanted to use the problem of military expenditure to put pressure on various factions, and after getting the desired effect, he resumed his post.
Song Ziwen's second resignation was on December 20, 1931, which was a true resignation. This resignation was an act to cooperate with Chiang Kai-shek's resignation. Previously, the Kuomintang had split into two governments, Nanjing and Guangzhou, and after the September 18 Incident, at the "Conference on Peaceful Reunification" held in Shanghai, the two sides reached a compromise agreement to reorganize the Nanjing government and realize the reunification of Ningbo and Guangdong. However, the Guangdong side insisted that Chiang Kai-shek go to the wilderness before going to Nanjing.
Under these circumstances, Chiang Kai-shek sent a telegram to the field on December 15 and resigned as chairman of the National Government. In order to show that he was advancing and retreating with Chiang Kai-shek, Soong Ziwen petitioned the Nationalist government on December 20 to resign as vice president of the Executive Yuan and minister of finance. At that time, Song Ziwen was replaced by Sun Ke and Huang Hailiang, but they soon stepped down without Song Ziwen's wrist. On January 30, 1932, the Nanjing government also appointed Song Ziwen as vice president of the Executive Yuan and minister of finance. Soon, Chiang Kai-shek also came back to power and cooperated again.
Song Ziwen's third resignation was on June 4, 1932. This resignation was caused by the problem of "suppressing the communists" military expenditure. After the September 18 Incident and the January 28 Incident, Chiang Kai-shek adopted the policy of "foreign countries must first be at home", believing that the Communist Party was a more dangerous enemy than the Japanese army. In the summer of 1932, as soon as the danger of war between China and Japan subsided, Chiang Kai-shek prepared a huge amount of military expenses and launched a large-scale campaign to suppress the Communists. Song Ziwen disagreed with this, believing that the anti-Japanese resistance was more important than "suppressing the communists," and the two had a conflict over the financing of military expenses for the suppression of the communists. Later, because Song Ziwen wanted to mobilize the 19th Army to Fujian, Song Ziwen and Chen Mingshu, the commander-in-chief of the 19th Route Army, resigned one after another and lived in seclusion in Shanghai, in order to change Chiang Kai-shek's attitude.
On the third day after Song Ziwen's resignation, Chiang Kai-shek, Wang Jingwei, and other important Kuomintang members met in Nanjing to discuss and decided to send a telegram to persuade him to "put the overall situation of the country first and continue to be responsible for maintenance." Although Song Ziwen has resigned repeatedly, he is still willing to compromise. On June 7, Wang Jingwei and others went to Shanghai to retain Song Ziwen, and Song Ziwen left a lot of rhetoric because he did not really want to resign. On July 7, a compromise was reached in Shanghai, and military spending increased from 13 million yuan per month to 15 million yuan, 3 million yuan less than the 18 million yuan originally requested by Chiang. Song Ziwen agreed to reinstate.
Song Ziwen's fourth resignation was in October 1933. In the summer of 1933, shortly after Song Ziwen returned from a visit to Europe and the United States, he resigned as minister of finance and vice president of the Executive Yuan. On October 29, the Kuomintang Central Political Council decided that Song Ziwen would resign as minister of finance and kong Xiangxi would take over. On the same day, the Standing Committee of the Kuomintang Central Committee decided that Song would resign as vice president of the Executive Yuan, and Kong Xiangxi would also take over, but retain Song's post as a member of the Standing Committee of the National Economic Committee and elect Song as a member of the State Government.
There is a theory that when Soong Ziwen went abroad, Chiang Kai-shek broke through his budget and spent all this money on the latest military operation to "suppress the communists." After Song Ziwen returned to China, he was very annoyed by this and hurried to see Chiang Kai-shek. The meeting finally caused a sensational quarrel, and finally Jiang slapped Song Ziwen in the face. Song Ziwen resigned from his post for this reason, and Kong Xiangxi replaced him as vice president of the Executive Yuan and minister of finance.
In fact, Soong's resignation was mainly due to differences in political views with Chiang Kai-shek. After consulting with Wang Jingwei and others, Chiang Kai-shek decided to further seek compromise with Japan, but Song Ziwen and others repeatedly expressed their opposition to Japan in public, and the contradictions could not be reconciled, and Song Ziwen's resignation was also reasonable.
Song Ziwen's resignation these 4 times illustrates a problem, he and Chiang Kai-shek are both dependent on and contradictory. When Chiang Kai-shek stepped down, he also stepped down, indicating that he was advancing and retreating with Chiang Kai-shek. However, when Chiang Kai-shek compromised with the Japanese and carried out large-scale military "encirclement and suppression" of the Communists, Song Ziwen disagreed and finally resigned. Moreover, it should be noted that Song Ziwen's attitude toward Japan was shaken, and this was only because he represented the interests of Britain and the United States in China, so in contradictory international affairs, he showed some enthusiasm for resisting Japan.
Source: The Complete Biography of Song Ziwen