The battle for Shanghai lasted three months. It was the largest and longest battle of the entire eight-year War of Resistance against Japan (1937–1945). During the first few days after hostilities broke out in Shanghai on August 13, 1937, the Chinese, with extraordinary martial ardor in the face of withering artillery fire from the naval vessels anchored in the river, drove the Japanese back to the shore of the Huangpu. Because of the neutrality of the International Settlement it was impossible for the Japanese to outflank the Nationalist troops until their expeditionary force opened a second front to the north between Wusong and Liuhe on September I. Even then, Chiang Kai-shek continued to pour his best troops into the duel. By October the Chinese had deployed seventy-one divisions and nearly all of the Central Army's artillery units, totaling half-a-million men. The Japanese forces, with six divisions and six independent brigades, only totaled 200,000 men, but their planes controlled the skies and their artillery was preponderant. Zhabei received the heaviest concentration of fire ever laid on one piece of earth until then in history. Yet the Chinese continued to hold their lines with a calm and incredible heroism remarked upon by all who witnessed their sacrifice. On November 5, a third front was opened when General Yanagawa Heisuke landed his Tenth Army (three divisions of 30,000 men) at Hangzhou Bay and drove inland to Songjiang behind the Chinese right flank, routing the Nationalists on November 9 along the Nanjing–Shanghai Railway where the Japanese air force had already destroyed most of the bridges. General Matsui Iwane's armored columns, no longer impeded by the rubble of Zhabei, turned retreat into slaughter.