The Jinan incident (traditional Chinese: 濟南慘案; simplified Chinese: 济南惨案; Japanese: 済南事件; formerly romanised Tsinan) or 3 May Tragedy (traditional Chinese: 五三慘案; simplified Chinese: 五三惨案; pinyin: Wǔsān Cǎn'àn) began as a 3 May 1928 dispute between Chiang Kai-shek's National Revolutionary Army (NRA) and Japanese soldiers and civilians in Jinan, the capital of Shandong province in China, which then escalated into an armed conflict between the NRA and the Imperial Japanese Army.
Japanese soldiers had been deployed to Shandong province to protect Japanese commercial interests in the province, which were threatened by the advance of Chiang's Northern Expedition to reunite China under a Kuomintang government. When the NRA approached Jinan, the Beiyang government-aligned army of Sun Chuanfang withdrew from the area, allowing for the peaceful capture of the city by the NRA. NRA forces initially managed to coexist with Japanese troops stationed around the Japanese consulate and businesses, and Chiang Kai-shek arrived to negotiate their withdrawal on 2 May. This peace was broken the following morning, however, when a dispute between the Chinese and Japanese resulted in the deaths of 13–16 Japanese civilians. The resulting conflict resulted in thousands of casualties on the NRA side, which fled the area to continue northwards toward Beijing, and left the city under Japanese occupation until March 1929.
During the Northern Expedition to reunite China under a Kuomintang (KMT) government, foreign concessions and consulates in Nanjing in March 1927 and Hankou in April 1927 were attacked by the KMT's National Revolutionary Army (NRA) soldiers and Chinese civilians respectively in what came to be called the Nanking and Hankou incidents. Following these incidents, NRA commander Chiang Kai-shek made repeated statements to the effect that he would not tolerate anti-foreign attacks by his soldiers, and the KMT foreign minister Huang Fu said that they would "protect to their fullest ability the lives and property of foreigners in China in accordance with international law and usage". Despite these assurances, foreign powers, including the Japanese, remained concerned about the safety of their economic and political interests in China, and resolved that the Nanking incident would not be repeated.
When the NRA forced back the Beiyang government-aligned "National Pacification Army" warlord coalition to Shandong province in May–June 1927, the Japanese, who considered the province within their sphere of influence, deployed four-thousand troops of the Kwantung Army to the cities of Qingdao and Jinan in what they called the "First Shandong Expedition" (第一山東出兵, Dai-ichi Santō Shuppei), ostensibly to protect Japanese civilians in anticipation of an NRA advance. NRA commander Chiang Kai-shek wanted to keep his troops away from Jinan, avoiding what he viewed as a useless and potentially costly clash with the Japanese. Similarly, Japanese prime minister Baron Giichi Tanaka knew that the deployment of troops could result in a conflict with the Chinese, which, rather than protecting Japanese citizens and economic interests, could further endanger them. As it happened, in an attempt to resolve the split between the Wuhan and Nanjing factions of the KMT, Chiang was forced to resign from his post of commander of the NRA and halt the Northern Expedition in August 1927, avoiding conflict. With the threat of the NRA advance gone, the Japanese withdrew their troops from Jinan in September 1927.
Chiang sought to avoid repetition of such conflicts and further Japanese interference, and on 5 November 1927, while he was nominally retired from leading the Northern Expedition, he met with Japanese prime minister Tanaka. During the meeting, Tanaka suggested that the Japanese would support only Chiang in China, and not interfere in Chinese domestic affairs. Chiang responded by saying he "understood" Japanese interest in China. When Tanaka said that Chiang should focus on consolidating his power in the territories under KMT control, rather than advance northward toward the Japanese sphere of influence in Fengtian clique-controlled Shandong and Manchuria, Chiang replied that this was not possible. The discussion, therefore, ended without a clear conclusion, though Tanaka was said to be hopeful for future meetings. Chiang, for his part, considered the meeting a failure, but maintained his approach of attempting to work with the Japanese to reach a solution that was amenable to both parties. Despite this, Chiang had only a tenuous hold on power in China, and relied in large measure on the promise to end foreign domination and re-unify the country to buttress his legitimacy.
By April 1928, Chiang Kai-shek had once again consolidated power, at which time he resumed the Northern Expedition. The NRA was able to quickly push back the forces of Beiyang-aligned warlord Sun Chuanfang, and advanced into Shandong. Sun retreated to Jinan by railway on 17–18 April, leaving the path to Jinan open to the NRA. When the Japanese learned of Sun's failure to defend Shandong, Prime Minister Tanaka, on the counsel of his military advisors, decided to deploy the 6th Division to Jinan on 19 April, in what was called the "Second Shandong Expedition" (第二山東出兵, Dai-ni Santō Shuppei). Whilst Tanaka had misgivings about whether it was prudent to launch the expedition, his party, the Rikken Seiyūkai, had run on a platform of "protecting nationals on the spot" in the February 1928 election, limiting his ability to moderate the Japanese response. Even before Tanaka had given the order, troops under the command of General Hikosuke Fukuda had begun arriving in Jinan via the Qingdao–Jinan railway, possibly as early as 10 April. This was the first serious case of unilateral action by the post-Meiji Restoration Japanese military. The first substantial group of 475 troops, however, arrived in Jinan from Qingdao on 20 April. They were followed by over 4,000 more troops over the coming days. The arrival of the Japanese troops in Jinan, just as the Beiyang-aligned forces had retreated there, prompted suspicions about whether the Beiyang warlords had asked for a Japanese intervention. This was used as propaganda by the Kuomintang, though Beiyang government leader Zhang Zuolin denied doing any such thing. Both the Beiyang government and the KMT government in Nanjing protested against the Japanese action, deeming it a violation of Chinese sovereignty.
As the NRA launched a pincer attack on Jinan, the railways to Qingdao and Beijing were damaged, preventing warlord-aligned troops from receiving reinforcements. This also brought the NRA in conflict with the Japanese, who were guarding the Qingdao–Jinan railway, though no violence broke out at this stage. On 29 April, chaos erupted as the warlord troops began to flee northwards across the Luokou Yellow River Railway Bridge, abandoning Jinan. As they left the city, the warlord forces were reported to have engaged in looting, though Japanese-inhabited areas continued to be protected by Japanese troops. Public dissatisfaction with the presence of the Imperial Japanese Army in Shandong became increasingly evident, their presence viewed as a new attempt by the Japanese to seize control of the region, as they had in 1914 during the First World War. NRA troops marched into Jinan over the course of 30 April and 1 May, and took control without trouble. On 2 May, Chiang Kai-shek began negotiations with the Japanese to withdraw their troops, gave assurances to Japanese Major General Ryū Saitō that there would be no disruption in Jinan, and ordered his troops to proceed northward from Jinan with haste, so as to avoid any potential conflict. Following the negotiations, Saitō decided to begin preparations to withdraw the Japanese troops, and said that all security matters in Jinan would then be entrusted to Chiang. General Fukuda later gave his approval to this decision, and the Japanese troops began withdrawal during the night of 2–3 May.