《明史·志·卷六十五》
又将步骑军分成中军，左、右掖，左、右哨，也称他们为五军。
又分步骑军为中军，左、右掖，左、右哨，亦谓之五军。
Also the mounted and foot divisions were divided into the central army, left and right flanks and left and right outposts, also known as them as five armies.