《明史·志·卷五十二》
十一年，改为留守中卫，增设留守左、右、前、后四卫，仍为亲军。
十一年，改为留守中卫，增置留守左、右、前、后四卫，仍为亲军。
In the eleventh year, it was changed to the Middle Garrison Headquarters, and four more were added: the Left, Right, Front, and Rear Garrison Headquarters, still as the Imperial Army.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 十一年，改为留守中卫，增置留守左、右、前、后四卫，仍为亲军。 [/INST] In the eleventh year, it was changed to the Middle Garrison Headquarters, and four more were added: the Left, Right, Front, and Rear Garrison Headquarters, still as the Imperial Army.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 十一年，改为留守中卫，增置留守左、右、前、后四卫，仍为亲军。
user
In the eleventh year, it was changed to the Middle Garrison Headquarters, and four more were added: the Left, Right, Front, and Rear Garrison Headquarters, still as the Imperial Army.
assistant