Battery
A battery is two of your pieces lined up on one file, rank or diagonal, with the rear piece backing up the front one so that both press on the same target.
What makes a battery work is addition. The front piece does the capturing or checking, and the piece behind it adds a second attacker and a second defender on the very same line. If the front piece is exchanged, the one behind simply takes over.
Typical shapes are two rooks doubled on a file or the seventh rank, a queen with a rook behind it on an open file, and a queen with a bishop behind it on a diagonal, often aimed at h7. The rear piece needs no open lines of its own, which is why batteries are cheap to build.
Order matters. A bishop behind the queen on the diagonal toward h7 supports a queen capture there, so the enemy king cannot recapture. Reverse the order, with the bishop in front, and you often get a discovered attack when the bishop moves.
To build one, line your pieces up on a line that leads to a target, then make sure nothing blocks it and count attackers against defenders on the target square. To fight a battery, block the line, cover the target square more times than it is attacked, or trade off the front piece.
In the diagram White plays Qxh7#. The queen on e4 and the bishop on d3 form a battery on the diagonal toward h7. The bishop guards the queen on h7, so the king cannot take it, the rook on f8 blocks the king's only flight square, and the queen covers h8.
A neighboring idea is Blackburne's mate. Blackburne's mate is a checkmate made with two bishops and a knight, where a bishop checks on h7 guarded by a knight on g5 while the other bishop on the long diagonal covers g7 and h8.
Also worth reading is Hook mate. A hook mate is a checkmate in which a rook gives check next to the king, a knight guards the rook, a pawn guards the knight, and one of the defender's own pawns blocks the last flight square.
A neighboring idea is Morphy's mate. Morphy's mate is a checkmate against a king in the corner in which a bishop gives check along the long diagonal while a rook controls the neighboring file, and the king's own pawn blocks the last flight square.
Knowing "Battery" helps most once you can spot it in a real game. A first lesson with George Li starts from your own games and finds the tactics you keep missing.
Related terms
An x-ray is hidden pressure: a bishop, rook or queen bears on a piece or square beyond an enemy piece in its way, and the pressure turns real once the blocker moves or is exchanged.
In a discovered attack one of your pieces steps off a line, and that move unmasks a bishop, rook or queen standing behind it, so a single turn produces two threats.
A mating attack is a sustained assault on the enemy king, usually built from several pieces and often with sacrifices, whose aim is checkmate rather than winning material.
A windmill is a repeating pattern in which a rook moves away to give a discovered check, captures a piece, returns with check, and repeats, winning another enemy piece with each swing.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
How much does chess coaching cost?
Published rates for private, group and subscription chess coaching, with the source and the date of each.
A game review, a read on your level and a written study plan from George Li.
Want to spot this in your own games?
A first lesson starts with your games: George reviews them and builds a study plan around what he finds.