to expand its occupation of China. These activities created a growing resistance against Japanese expansion. The Marco Polo Bridge Incident of 1937 marked the beginning of full-scale hostilities between the Republic of China and the Empire of Japan. Japan's occupation of China was declared illegal by the League of Nations; however, it was not able to pass sanctions to cease the occupation as Japan had withdrawn from the league in 1933. In China, the Second Sino-Japanese war is known as the “war of resistance”. Research of the weapon Japan had signed the Geneva Protocol, which prohibited biological and chemical warfare, but it had not ratified the treaty and was thus not bound to the conditions of the treaty. Not being bound to the protocol therefore allowed Japan to develop a chemical and biological weapons program. This program, under Japan's top-secret weapons program, was founded and led by General Shirō Ishii. Ishii played a large role in pushing for the funding of the biological weapons program from the high command. General Ishii was said to have been an “eccentric ... flamboyant and arrogant man”. Ishii was accepted into the medical department of Kyoto Imperial University, where he demonstrated his fast and quick mind, much advanced for his age. Throughout university, Japan instilled a solid sense of nationalism and patriotic duty into the students. General Shirō Ishii has been described as an "ardent ultra-nationalist". Ishii understood science and medicine as an avenue to further Japan's nationalistic goals. He joined the army where he was appointed lieutenant. Along his journey, Ishii created a network of ties with people of high standing in university and the military; these connections would later facilitate the founding of the biological weapons program, and subsequent research. His argument for the use of chemical weapons was that biological warfare would be a cheaper alternative to traditional forms of weaponry. The main units of this program were units 731 and 1644. Both units operated under the guise of the Epidemic Prevention and Water Purification Department in the Imperial Japanese Army, and had the public mission of preventing the spread of disease through monitoring Japan's water supply. Much of the research and experimentation took place in China and Manchukuo, although some experimentation also occurred at Imperial Navy hospitals and hospitals where wounded soldiers were being treated for their injuries. Experimentation occurred at these hospitals on islands across the Pacific wherein various