When the Chinese garrison refused, the Japanese 8th Division issued an ultimatum, and then attacked the pass with the support of 4 armored trains and 10 tanks.[2] The Japanese attack was supported by close air support from bombers, and by shelling by warships of the Imperial Japanese Navy's IJN 2nd Fleet with a dozen warships offshore. On January 3, Chinese regimental commander Shi Shian, unable to withstand this attack, was forced to evacuate from his positions after losing half of his force.[2]