A battery in chess is a formation that consists of two or more pieces on the same rank, file, or diagonal.
It is a tactic involved in planning a series of captures to remove the protection of the opponent's king, or to simply gain in the exchanges.
"[1] However, in Chessgames.com blogs and game annotations of other chess websites, the term is also used in cases where moving the middle piece will uncover a threat other than a check along the opened line.
[2] It is particularly effective to form a battery using rooks because they may be combined to occupy the same rank or file.
In some chess openings, the queen is often involved in the set up, and becomes part of a battery but is reserved for the final capture in the series of exchange of pieces.