Perpetual Check

Perpetual Check

There are different types of checks in chess, but what exactly is a perpetual check? Is it what it sounds like? Let's find out!

Here is what you need to know about perpetual check:


What Is A Perpetual Check?

A perpetual check is precisely what it sounds like: a series of checks that could theoretically last forever. Luckily, chess has a rule known as "threefold repetition," which states that a game ends in a draw if an identical position is reached three times in the same game, avoiding the silly notion of sitting at the chessboard indefinitely against an obstinate opponent!

In the following historic game between GM Bobby Fischer and GM Mikhail Tal, the game ended in a draw after Tal's 21... Qg4+:

Why did this game end in a draw? It ended because of the perpetual check that occurs next—the position will be repeated three times and the game will end in a draw.

perpetual check
White cannot avoid the perpetual check!

Please note that no matter what White does, they cannot escape the series of checks from the black queen. Now that you know what a perpetual check is, you may be wondering, "Why are perpetual checks important?" 

Why Are Perpetual Checks Important?

Understanding and recognizing perpetual checks are important because they can save a player from losing, and also because we want to avoid perpetual checks if we are winning! In the following position, Black is ahead a lot of material, but it is White's move. What would you play?

perpetual check
White to move.

Only through a perpetual check can White save the draw! After Qe8+, Black must reply with Kh7, and the pattern repeats itself—the draw is inevitable, and White has saved the game!

perpetual check
A perpetual check can save you from a losing position.

What if you are the side that has a large material advantage and wants to avoid a perpetual check? Let's pretend that it is Black's move in the same position. How can you save yourself from the perpetual check that begins on e8?

perpetual check
Black to move and stop the perpetual check.

There are a few ways to stop the perpetual check, but the simplest is to stop the check on e8 with either Rb8 or Kf8.

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Both Rb8 and Kf8 stop the perpetual check.

Test

Now that you know what a perpetual check is, why perpetual checks are important, and how they can save you from a lost game, let's put your new skills to the test!

In the following position, Black has just played a6-a5, and White is down a full rook and a passed pawn. How can White save the position with a perpetual check?

perpetual check
How can White save the position?

Yes! Qf7+ forces a perpetual check!

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Qf7+ begins a perpetual check!

After Qf7+ Black must reply with Kh8, and the checks continue until threefold repetition occurs and the game ends in a draw. Here is the entire perpetual check sequence:

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Perpetual check saves the day!

Conclusion

Because you now know what a perpetual check is and why perpetual checks are important, you can recognize potential perpetual checks, and you understand how a perpetual check can save you from losing a lost position. Use this new knowledge in your own games, and may you save many positions with perpetual checks!