The step army commanded the yamen, known as the "Commander of the Fifth Battalion of the Nine-door Step Army", and was the capital of the Rongwei Army. Responsible for guard, inspection, entrance guard, night patrol, prohibition of alcohol, armor protection, arrest, trial of cases, imprisonment of criminals, firing signal guns and other important positions in Beijing.

Nine gates refer to Dongzhimen and Chaoyangmen in the east; Xizhimen and Fuchengmen in the west; Deshengmen and Andingmen in the north; Chongwenmen, Zhengyangmen (front gate) and Xuanwu Gate in the south. Collectively called "inner nine" and "inner city", the nine magistrates have great power, which is equivalent to the garrison commander, that is, the person in charge of the inner city.

The former nine magistrate yamen is located in Chongwenmen.

Jianrui Camp: In March of the 12th year of Qianlong (AD 1747), the chieftain Shaban in Dajinchuan rebelled, and Qianlong sent Zhang Guangsi to Yunnan to counter the rebellion. Due to operational needs, the Eight Banners forward was ordered to practice ladder skills with thousands of strong and brave people selected from the guards. After the war, Qianlong ordered the ladder soldiers not to set up camps, so he built Ruiying. It was fourteen years ago. The 1000 ladder soldiers in Jianrui camp are divided into left and right wings, each with a 1 wing collar, and 50 pioneer schools, all under the control of the president. Camp Jianrui has 3,800 soldiers. The duty of Jianrui Camp is to be a wing team when reading a lot and balance the gun camp outside the meeting. Always be ready for the guards of Jingyi Garden. Patrol is a follower. "