Battalion

A battalion is a military unit that in size and organisation is between a company and a regiment.

Breen Confederacy
The equivalent of a battalion in the Breen military was called a uhon (or unhareh). These were often sub-legions of large legions fielded by the Breen and commanded by a nareg (major/colonel). 

Cardassian Union
A pesh'dar was the Cardassian equivalent to a battalion and was made up of around 1,000 soldiers commanded by a dal. 

Dominion
A battalion in the Dominion is comprised of three formations numbering 729 Jem'Hadar and commanded by a Suba'atorn. 

Klingon Defense Force
A Klingon Defense Force battalion is approximately 500 warriors commanded by a HoH (captain). 

Romulan Star Empire
A tresh'val is the Romulan equivalent to a battalion and was formed around a group of unsha'val (brigades) and was between 3,000 - 5,000 soldiers with a colonel in command. 

Starfleet Ground Forces
A Starfleet Ground Forces battalion is between 200 and 2,000 Starfleet soldiers and is typically commanded by a captain or major. (LUG RPG: )