公元1937年7月7日,永定河畔的卢沟桥头。嘈杂了一天的中华民国河北省的小城——宛平县城迎来了一个没有月光的闷热夏夜。当晚,又淅淅沥沥下起了雨。在夜色和雨幕掩护下,宛平城东北不远处,数百名全副武装、身材粗短精悍的军人却在紧张地进行一场夜间攻防战的演习。偶尔可以听到他们发出简短的口令: July 7, 1937 AD, Yongding River Lugou bridge. Noisy day of the ROC town of Hebei Province - Wanping County ushered in a sultry summer without moonlight. That night, it was raining again. Under the cover of the night and the rain curtains, not far from the northeast of Wanping City, hundreds of heavily armed and stubborn military personnel are nervously conducting a night offensive and defensive war exercise. Occasionally you can hear them issue a brief password: