[6] 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.

[7] 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.

[8][9] 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.

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.

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.

[12] 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.

[14][15] 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.

[16] Even before Tanaka had given the order, troops under the command of General Fukuda Hikosuke had begun arriving in Jinan via the Qingdao–Jinan railway, possibly as early as 10 April.

[17] As the NRA launched a pincer attack on Jinan, the railways to Qingdao and Beijing were damaged, preventing warlord-aligned troops from receiving reinforcements.

On 29 April, chaos erupted as the warlord troops began to flee northwards across the Luokou Yellow River Railway Bridge, abandoning Jinan.

Chiang, who was not interested in conflict with the Japanese, and wanted to continue the Northern Expedition, agreed to withdraw his troops from the city, leaving only a small number to keep order.

[22][27] On 4 May, however, the Japanese reported that their chief negotiator, Colonel Sasaki Tōichi, was robbed and nearly beaten to death, and only saved by intervention of one of Chiang's officers.

[27] Responding to a request from General Fukuda, Prime Minister Tanaka ordered the despatch of reinforcements from Korea and Manchuria in the "Third Shandong Expedition" (第三山東出兵, Dai-san Santō Shuppei), which began arriving in Jinan on 7 May.

[2] The period of occupation was defined by oppression, with freedom of the press and assembly proscribed, postal correspondence censored, and residents killed for alleged sympathies with the KMT.

[36] When Chiang lectured a group of Chinese army cadets on the subject, he urged them to turn their energies to washing away the shame of Jinan, but to conceal their hatred until the last moment.

Chiang's troops, however, continued to expand their control in northern China and the Japanese army's distrust of the forces of Chinese nationalism would only grow.

[38] According to historian Akira Iriye, the Jinan incident demonstrated the weak nature of the Japanese chain of command, and the powerlessness of civilian government officials to stop unilateral aggression by the military.

[39] Japanese army leaders, increasingly outside civilian control, feared that Chiang would respond to patriotic agitation and threaten their interests in southern Manchuria.