This wall in Nanjing, Jiangsu province, east China, was built over 600 years ago. This historic scenic spot should be carefully preserved. However, it's been riddled with bullet holes. These "scars" were caused by Japanese aggressors. On Dec. 13, 1937, the Japanese invaders captured Nanjing City. Over six weeks, these soldiers killed around 300,000 Chinese civilians and unarmed soldiers. The massacre was one of the most barbaric episodes of World War II. On Dec. 13, 2014, President Xi Jinping attended China's first state ceremony to commemorate more than 300,000 Chinese murdered by Japanese aggressors during the Nanjing Massacre.