日本军国主义挑起卢沟桥事变，目的是要先占领北平和天津，藉以控制华北，继而妄图灭亡中国。７月２７日，日本参谋本部命令中国驻屯军以现有兵力进攻平、津地区的二十九军。２８日，二十九军军长宋哲元命令所属将士准备全线抵抗；并通电全国表示：在国家存亡、千钧一发之... Japanese militarism provoked the Marco Polo Bridge Incident, the purpose is to occupy Peiping and Tianjin, in order to control North China, and then vain attempt to perish China. On July 27, the Japanese General Staff Command ordered Chinese Tunjun troops to attack the Twenty-ninth Army in Ping-Jin area with their existing troops. On the 28th, the commander of the XX Army, Song Zheyuan, ordered his soldiers to prepare for resistance across the board and energized the country to express his belief that in the country’s survival,