Before the Battle of Rehe, Rehe was nominally controlled by the central government of the Republic of China, but in reality it was Rehe Province controlled by the Fengcian warlords (renamed the Northeast Frontier Defense Force after the Northeast Revolution). Rehe Province is located to the north of the Great Wall and borders Liaoning, Hebei, Chahar and other provinces. After the September 18th Incident, Rehe Province became the rear base for the remnants of the Northeast Army and the Northeast Anti-Japanese Volunteer Army. Since when Manchukuo was founded, it was stated in the Declaration of Founding that all the four northeastern provinces north of the Great Wall and outside the Pass were the legal territory of Manchukuo. Rehe was part of Manchuria. The Japanese army was stationed outside the Great Wall. It was quite obvious that they would occupy Rehe and march directly to Peiping. As long as they occupied Rehe, the Japanese army could choose a shorter route besides Shanhaiguan to go south and march directly to Peiping.