BEGINNING WITH KOREA and continuing into Manchuria, expansion of Japan's interests and sphere of influence on the continent was the theme that preoccupied Japan nonstop from the latter part of the nineteenth century through the first half of the twentieth. In the course of the bloody wars waged against China in 1894–1895 and against Russia in 1904–1905 Japanese acquired what was to become a deep-seated obsession that the very survival of the nation depended upon control of the Korean peninsula and that its sway over Korea would be in peril if Manchuria were not secured as well. The idea of invading and occupying Korea (known as “Seikanron”) debated at the beginning of the new Meiji regime was no more than an expression of the naive desire for survival of a still-weak and untried state just beginning to open its eyes to what was going on in the world. But as time went on, that idea of placing Korea – and Manchuria – under Japan's control became a strong demand of the people of what was now a world power. It became embedded in the minds of people of all political persuasions as the righteous claim won through the bloody toll of repeated wars and driven by intense patriotism.

The lives of countless men – the fathers, husbands, and sons of households – were lost in the pursuit of expansion into the continent. To support such wars waged with every passing decade, people put up with horrendous sacrifices and harsh austerities, well aware that they would have to endure those hardships for still more years to come, and determined to do so.

After the Sino-Japanese War, the Liaodong Peninsula Japan had won at the cost of much blood and sacrifice was snatched away due to what was seen as China's scheming and the intervention of Germany, France, and Russia. When the Western powers failed to stand behind Japan's right to territory it had won in battle, Japanese learned the folly of such trust. The experience of having won territory at great sacrifice only to have it taken away by the collusion of other powers became an unforgettable sore spot that would rankle in Japan's diplomatic relations from then on.