During the First World War (1914-1918), China experienced colonial conflicts by Japan and some European countries that wished to have a foothold in China that had lived in long isolation, so the Japanese threat emerged clearly after the withdrawal of German troops from the Shandong Territory and some of the leased islands captured by Japan and disembarked in 1914. Japan exploited the conditions of World War I and imposed on China the 21st demands in 1915, which were rejected by the Chinese people. After the war ended, China sought to recover what China had previously lost through the Paris Reconciliation Conference in 1919. After intensive efforts by the Chinese negotiating delegation, it was unable to restore Shandong territory and other regions and failed to convince all members about their claims. In the aftermath, massive protests broke out in China, which then spread to most parts of the country, called the Fourth of May Movement, which denounced the conference's decisions, which were described as humiliating. Many thinkers, traders and crafts were organized into that movement, through which the Communist Party was able to entrench its roots in the Chinese middle after being welcomed by most segments of society.