a large group of soldiers consisting of several companies (company).——朗文当代大辞典

A large body of men in battle array; one of the large divisions of an army.——牛津当代大辞典

The main body of an army.——牛津当代大辞典

A body of infantry (or engineers) composed of several companies, and forming part of a regiment. (The number of battalions in a regiment varies greatly in different countries, and even in the British Army at the present time.)——牛津当代大辞典  @en