Double check in chess
Two checks at the same time, and the king has to move. No other answer is legal.
Play through Reti-Tartakower → Vienna, 1910: the queen sacrifice and the double check that follows it.
A double check is a discovered check where the moving piece also gives check, so two pieces attack the king simultaneously.
Why the king must move
There are only three legal answers to a check: capture the checking piece, block the line, or move the king. Against a double check, capturing removes only one checker and blocking stops only one line. Only the king move can deal with both.
That is why in a double check, material does not matter. Both checking pieces can be left hanging, because only the king can take one, and only if that piece stands next to the king with no defender.
Because the king is forced to move, a double check can drive it onto a square where it gets mated. Philidor's legacy, the classic smothered mate, uses one to send the king back into the corner, and the queen sacrifice below works the same way.
How to create one
- Line up a bishop, rook or queen on the enemy king's file, rank or diagonal with one of your own pieces in between.
- Find a move for the in-between piece that also gives check. A knight is well suited to this, because every knight move leaves the line, so you only need one that lands on a checking square.
- The moving piece does not need a defender unless it lands next to the king, where the king could take it.
The famous example
Reti-Tartakower, Vienna 1910. After 1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nf6 5.Qd3 e5 6.dxe5 Qa5+ 7.Bd2 Qxe5 8.O-O-O Nxe4, White played 9.Qd8+!!, and after the forced 9...Kxd8, 10.Bg5+ is a double check. Black can neither capture a checker nor block, and both king moves allow mate: 10...Kc7 11.Bd8# and 10...Ke8 11.Rd8#.
The queen sacrifice only works because the follow-up is a double check. Against a single check, Black could block it and stay a queen and a knight up.
Practice the double check
Reading about a pattern is not the same as spotting it under time pressure. The free chess puzzles trainer serves rated positions from real games and adjusts to your level as you solve. When you get one wrong, press Analyze once the puzzle is over to open it on the analysis board and see what you missed.
Related tactics
Discovered attack
Move one piece and a different piece behind it makes the threat. The piece that moved can make a threat of its own, so one move often creates two attacks.
Smothered mate
In one of the prettiest mates in chess, a knight checks a king that cannot move because its own pieces fill every square around it.
Back rank mate
A castled king behind three unmoved pawns has no square to step up to. A rook or queen that checks it along the back rank is mate unless something can capture the checker or block the check.
Frequently asked questions
Can you block a double check?
No. Blocking stops one line, and the other checking piece still attacks the king. The king must move.
Can you capture a piece giving double check?
Only with the king, and only if the checking piece stands next to it with no defender. A capture by any other piece leaves the second checker still giving check, so it is illegal.