The real start of the Second World War?

For many in the west, the Second World War started with Hitler’s Invasion of Poland on 1 September 1939. However, some historians consider the start of the Second Sino-Japanese War as the actual start due to both sides’ active involvement in the wider, worldwide struggle. Japan was one of the main three Axis powers and China fought alongside the Allies.

Starting in 1937, the conflict between the Empire of Japan and Republic of China became part of the wider Pacific Theatre of the Second World War after the Japanese attacks on Malaya and Pearl Harbour in 1941. Throughout the conflict, China received aid from the Soviet Union - who had a long-standing rivalry with Japan – and the United States.

Residents of Canton, the city now known as Guangzhou, run for cover as the Japanese bomb the city, circa 1937-  1941.


The origins of this conflict can be traced back to the First Sino-Japanese War which took place in 1894 – 1895. China was ruled by the Qing Dynasty at that point and was no match for the modernised Japanese army which defeated its forces.

As part of the peace terms, China was forced to give control of Taiwan to the Japanese and guarantee the independence of Korea, which was agreed at the Treaty of Shimonseki.

This led to the eventual collapse of the Qing Dynasty – which was already weakened by internal problems and external, foreign influence - and the formation of the Republic of China.

The Second Sino-Japanese War was sparked off by the Marco Polo Bridge incident which took place on 7 July 1937, when an ongoing dispute between the two countries escalated into a full-scale invasion by the Japanese.

Prior to this, there had been a long-standing enmity between the two countries and the Japanese expansionist policy had aggravated this as the Empire wished to expand both its political and military influence.

After the First World War, Japan’s production struggled due to the effects of the Great Depression and increased textile production from China, its people sought greater rights for workers and its exports had started to slow.

The Empire needed to secure raw materials, food, and labour from outside its borders and China – with its huge population and landmass, but relatively weak military, was a tempting target, especially for the new militarist faction – led by Hideki Tojo – that had come to power in Japan.

Furthermore, since 1930, the Republic of China was embroiled in its own internal conflict. Its ruling nationalist party, the Kuomintang, led by Chiang Kai-shek – was locked in a civil war with the Chinese communists who had rebelled against its rule. This breakaway faction, the Communist Party of China (CCP) was led by Mao Zedong.

Chiang Kai-shek, Chairman of the Military Affairs Commission, the Republic of China.

Mao Zedong
Chairman of the Chinese Communist Party.


The first step was the invasion and annexing of the Chinese region of Manchuria, which after the defeat of Chinese forces, came under Japanese control as a new puppet state – Manchukuo – in 1931, after the events of the Mukden Incident.

Some historians consider this the actual start of the Second-Sino Japanese War. Certainly, from this point onwards until 1937, Japan and China were engaged in a series of small scale local clashes and skirmishes – often referred to in political speak as ‘incidents’.

The Japanese puppet state of Manchukuo.


Outbreak of war

The general consensus is that the war started in 1937 with the aforementioned Marco Polo Bridge Incident and what followed was a series of Japanese victories, in which they conquered the major Chinese cities of Bejing, Shanghai and Nanjing and committed horrific atrocities in the latter, the the so called ‘Rape of Nanjing’ – described as one of the worst atrocities of the Second World War.

After defeat at the Battle of Wuhan, the Chinese government relocated to Chongqing which lay further west. Help started to arrive for the Chinese after they signed the Sino-Soviet pact in 1937 with the Soviet Union sending materials to aid the Chinese Nationalist Army.

The Chinese Air Force also resisted strongly against the invaders and were later joined in their efforts by American mercenaries such as the ‘Flying Tigers’.

A Curtiss P-40  'Flying Tiger'


By 1939, the Chinese – the Nationalist and Communists having put their differences (temporarily) aside and supported by the Soviet Union and the USA, were faring much better against the Japanese, who were increasingly finding their forces stretched thin over the vast expanses of China.

Eventually, a stalemate of sorts developed, with the Japanese in control of the major cities and having cut off sea access to the Chinese capital, further isolating it, but lacking the manpower to control the vast tracts of countryside which contained countless towns and villages.

In November 1939, the Nationalists launched a large-scale winter offensive against the Japanese and in August 1940, it was the turn of the Chinese communists to strike at the Japanese in central China. In further support of China, the still officially neutral USA were now preventing the sale of an increasing number of their resources to Japan, including steel and oil.

It was this boycott which pushed Japan – facing the prospect of dwindling oil supplies - into declaring war on the USA with the surprise attack on Pearl Harbour in December 1941.

Japanese soldiers wearing gas masks during the conflict.

The tide starts to turn

Now officially at war with the Axis powers, the United States increased its aid to China with the Lend-Lease act, giving a total of $1.6 billion (equivalent to $18.4 in todays money) to support the Chinese war efforts, often air-lifting materials over the Himalaya mountains to avoid flying over Japanese controlled Burma.

The Japanese tried to retake the initiative with Operation Ichi-Go in 1944 – the invasion of Henan and Changsha but the now better equipped Chinese were able to hold out and avoid having to surrender.

The following year, the Chinese Expeditionary Force advanced in Burma and forged a land link with India. Chinese counteroffensives in southern China retook West Hunan and Guangxi and by the 2 September 1945, Japan was forced to formally surrender.  

China ended the war recognised as one of the ‘Big Four’ allied powers – alongside the USA, Soviet Union, and the UK. It regained its lost territories and became one of the five permanent members of the post-war United Nations Security Council.

A Chinese "comfort girl" shortly after being freed. Rangoon, China, 8 August. 1945.


The Second Sino-Japanese war was the largest Asian war in the 20th century with anything from 10 to 25 million civilian casualties and around 4 million military ones – dead or missing, it has been described as ‘the Asian holocaust’. It was responsible for the majority of casualties in the whole of the Pacific theatre of war.