How did the social impacts led to nationalism?

On 23rd December, President Chiang Kai-Shek in Nanking issued an appeal to all Chinese nationalists in Malaya (especially members of the Kuo Min Tang) to rally behind the British in resisting the Japanese. The British initiated a belated rapprochement with their erstwhile local foe, the Malayan Communist Party (MCP). They reached an agreement 10 days later on the training of communist guerillas to fight behind enemy lines in the event of the Malayan Peninsula being overrun by the Japanese, a prospect which seemed imminent.

Cooperation was established between British leaders and nationalist groups. Sir Shenton Thomas, Governor of Singapore, even lifted the ban on the MCP, KMT and other Chinese associations. Cooperation between nationalist groups and British leaders gave the nationalist groups a chance to rise up as they were not suppressed.This allowed the nationalist groups to strengthen and expand their organization, leading to the development of a sense of unity among the people. This gave them the ability to develop nationalistic sentiments. 

The Japanese implemented a policy which favoured Malays over Chinese and Indians.- Japanese replaced the British civil servants. In the smaller Straits Settlements, where a larger number of non-Malays were employed in the British Civil Service, pre-war officials of all races continued to hold office in 1942-1943, but Malay officials increased rapidly. For example, in the Koa Kunrenjo (leadership training schools) that were established, 70% of trainees were Malays and were given high appointments. This caused people to resent Japanese rule because they felt disadvantaged. This resulted in a sense of disunity in the people.

Video on the Japanese Occupation in Singapore.

Widespread of looting and crime (lawlessness), led to "Sook Ching" (purification), to wipe out operations against "anti-Japanese elements", especially the Chinese. Kempetai troops moved further into the rural districts they indiscriminate and tended to regard all Chinese hostile, leading to massacres. 6000 to 40000 Chinese were killed during the Sook Ching process. The Chinese population were alienated from the Japanese administration. The army continued to treat the Chinese population with the greatest severity for war. The Sook Ching drove hundreds of Chinese youths and men into the jungles to join the communist-led resistance movement, MPAJA. MPAJA then gained control of Malaya, but they tortured Chinese who were suspected of being informants of the Japanese.

The Indians were treated better by the Japanese, as they needed the support of the Indians. Japanese authorities promised to free India from British. This formed the India Independence League and the India National Army. Japan tried to invade India in 1943 but they failed. The Indians also suffered. 250000 were forced to work in death railway, 10000 died. This led to the growing hatred towards the Japanese and distrust of Japanese

• -Many joined resistance group