On Second Thought: 70 years on, the world has still not learnt lessons of war
By the time Hitler raided Poland in 1939, starting the second world war, China had been fighting Japan for eight years

This year marks the 70th anniversary of the end of the second world war. China suffered tremendously during the conflict.
Japan's military action against China began in 1931 when it seized three provinces in the northeast. The following year, the Manchukuo was set up to run the newly colonised region. Puyi, the last emperor in the Qing dynasty that ruled China before the 1911 revolution, was made the figurehead of the puppet state.
By the time Hitler raided Poland in 1939, thus starting the second world war, China had been fighting Japan for eight years, all by itself and with millions of casualties.
Why had other world powers tolerated Japan's aggression for so long without any attempt to stop it? They would certainly have done so in the earlier part of the century, not out of justice but out of greed to prevent the spoils of the war from being taken by Japan alone.