Chang Tso-lin had accepted a loan from the Japanese. For this reason and because of certain plans of their own, they were determined to protect him. The end of the World War had loosened their grip on China; the Treaty of Versailles and the Nine-Power Treaty had cancelled their Twenty-one Demands. Nevertheless the Japanese were still in Tsingtao, and their presence in other areas of the North, while not exactly covered by written documents, was not disputed as long as the Old Marshal remained on friendly terms with them. This presence was one barrier against Chiang's making a rapid finish to his Northern Expedition, and there were two more--the Hankow forces, whose general had pulled them together and was now advancing on Nanking from the west, and the defection of that arch-defector Feng Yü-hsiang, who had promised to attack Chang Tso-lin but later changed his mind.
The Nationalists had entered Shantung and were on the last push to Peking when, as Chiang was about to lead them into Tsinan near Tsingtao, he found the way blocked by Japanese troops. He did not feel ready to take them on, and the army fell back on Hsuchao; in a short time the Northern forces had pushed it back nearly to Nanking. This reverse alarmed and angered lesser generals, and Chiang's leadership, which had survived much strain during the violent interruptions of the summer, now began to totter. The generals quarreled with him . Chiang, veteran of many such resistances, realized that the time had come to stage one of his withdrawals. He resigned from the army as he had so many times in the past, and retired to his native hills. To newspapermen who followed him he made several statements: It had been said that be sought Russia's friendship and advocated co-operation with the Communists until the break. He wished to refute this. He had always