On 30 May 1925, Chinese students in Shanghai gathered at the International Settlement, and held demonstrations in opposition to foreign interference in China. Specifically, with the support of the KMT, they called for the boycott of foreign goods and an end to the Settlement, which was governed by the British and Americans. The Shanghai Municipal Police, largely operated by the British, opened fire on the crowd of demonstrators. This incident sparked outrage throughout China, culminating in the Canton–Hong Kong strike, which began on 18 June, and proved a fertile recruiting ground for the CCP. Concerns about the rising power of the leftist faction, and the effect of the strike on the Guangzhou government's ability to raise funds, which was largely dependent on foreign trade, led to increasing tensions within the United Front. Amidst this backdrop, Chiang, who had been vying for the position of KMT leader, began to consolidate power in preparation for an expedition against the northern warlords. On 20 March 1926, he launched a bloodless purge of hardline communists who were opposed to the proposed expedition from the Guangzhou administration and its military, known as the Canton Coup. At the same time, Chiang made conciliatory moves toward the Soviet Union, and attempted to balance the need for Soviet and CCP assistance in the fight against the warlords with his concerns about growing communist influence within the KMT. In the aftermath of the coup, Chiang negotiated a compromise whereby hardline members of the rightist faction, such as Wu Tieh-cheng, were removed from their posts in compensation for the purged leftists. By doing so, Chiang was able to prove his usefulness to the CCP and their Soviet sponsor, Joseph Stalin. Soviet aid to the KMT government would continue, as would co-operation with the CCP. A fragile coalition between KMT rightists, centrists led by Chiang, KMT leftists, and the CCP managed to hold together, laying the groundwork for the Northern Expedition.