Lim Bo Seng, despite his privileged background and success as a businessman, was staunchly anti-Japanese even before the war came to Malaya. An active contributor of the China Relief Fund, he was later the Director of the Labour Service Department in the newly formed Singapore Chinese Mobilisation Council. Certain to be a target of reprisals for the Japanese, he was compelled to flee Singapore just before it capitulated. He managed to reach Sumatra where he then made his way to Colombo and finally to Calcutta in India. There, he met a British officer, Basil Goodfellow, who persuaded him to join the British efforts in setting up a joint China-Britain espionage network in Malaya. He then proceeded on to Nationalist China to recruit overseas Malayan Chinese for this task. This resistance network came to be known as Force 136.
He was held in high regard by the British and other members of Force 136 for his patriotism, leadership and organisational abilities. After receiving training from the British in India, the men of Force 136 were inserted into Malaya via submarine in batches. Appointed leader of the Malayan Chinese section, he personally arrived in Malaya in November 1943 to co-ordinate the efforts. He was one of the five signatories in the Bukit Bidor Agreement signed on 1st Jan 1944 where the British and the Malayan Communist Party agreed to work together and support each other against the Japanese.
Tragedy was to strike when he was stopped at a checkpoint at Gopeng and arrested. He had earlier ignored warnings and pleas from his comrades about the danger of his mission, which was to revamp the entire intelligence network and solicit funds from his wealthy friends. Brought to Batu Gajah Prison, he was subjected to continuous interrogations and torture by the infamous Kempeitai. Lim Bo Seng was already weak in health, having just gone for a haemorrhoids operation in India before arriving in Malaya. To make matters worse, he suffered from dysentery. Finally, on 29th June 1944, he succumbed under the immense suffering and passed away.