X-Ray Attacks: Hidden Pressure, Sudden Impact

Many tactical ideas in chess revolve around direct contact between pieces. Think about forks, pins and double attacks. Others are based on what hides beneath the surface. As followers of this blog know, this is what we like to explore, and X-rays definitely belong in this second category. They sit within a broader group of ideas that reward deeper board vision. These concepts often go unnoticed until they suddenly catch even strong players by surprise.

So what exactly is an X-ray in chess?

As the name suggests, an X-ray involves a piece indirectly controlling a square through the body of an opponent piece. The pressure exerted from the X-ray is therefore camouflaged but is applied as soon as the opponent piece is forced to move. The basic theme can be seen in below introductory example:

Re8 is not directly controlled by any white pieces and is guarded by Blacks Qb5. However e8 is X-ray'ed by our Qa4, so it is still indirectly within our Queen's line of sight. The pressure is still exerted along the diagonal through Blacks Queen. When Qb5 is forced to take on e8, it opens up for our Qa4, making the move Re8 possible. Understanding this theme opens up for many hidden tactics!

This article is part 1 of 2 of my lessons covering the X-ray. In a follow-up article I will explore X-rays as a defensive motif, something that is far less charted. There we will look at unexpected defensive resources via the X-ray that saves you position. Do follow this blog to make sure you are notified when that lesson drops! (EDIT: It’s up, check out part 2 here! X-Ray Defence: Hidden Resource, Sudden Lifeline)

In this article I have gathered 7 instructive exercises based on X-ray attacks with increasing difficulty and from many different angles.

Position 1: White to play and win

To understand this tactic it's important to see that Qf8 is directly supported by Ng6 but it is also Xray'ed by Rf1 through Blacks defender. We must note that the f8 square is still within our Rooks line of sight and the indirect pressure from Rf1 can be utilised. The next example is similar mating attack but from a different angle:

Position 2: Black to play and win

This example was a little harder, as Qg1+!! seems like such an unnatural move. We need to understand the concept that although there is a defender in the way, the g1 square is X-ray'ed by our Re1 through White's defender allowing for an unexpected back rank mate. I have previously written an article specifically addressing Back rank tactics you didn't see coming, if you are interested in more of these.
Lets now explore X-rays via diagonals:

Position 3: White to play and win. Black is up a pawn and has strong central control, but there is a hidden vulnerability:

Yet another unexpected shot, but the alignment is there. Ne5 is within our Bc3's line of sight through Blacks Bd4 and it comes to life after the beautiful Queen sacrifice producing an elegant Mate in 3.
Of course, the X-ray theme is not just limited to mating attacks. Lets look at X-ray's attack that win for other tactical reasons:

Position 4: White to play and win. Should we trade Queens or can White take advantage of Blacks lack of development?

Bb5 is a very surprising move as the b5-square seems to be double protected, but if Black takes with the Queen it unleashes Whites X-ray from Qg5, while the a-pawn doesn't actually defend b5 due to the pin on the a-file. (See the lesson "Pinned Pieces don't defend" for other examples like this)

Position 5: Black to play and win. Do we trade queens, grab the f2 pawn or is there something lurking?

If you were able to solve all so far, well done! If not, I hope pattern recognition has kicked in and you have developed an eye for looking for these motifs. That is the intention of this lesson! For the final 2 examples we ramp up the difficulty a little as the variations will be a little longer. Try to work out til the end of the variation and evaluate the position before making the first move.

Position 6: White to play and win. Black has turtled up, but can we break through?

Rxg6 lured Blacks Queen into the vision of Qf7 which then X-rays the h5 square through Qg6, winning decisive material and cracks the fortress. For the final example we know of course there is an X-ray in there, but try to work out Whites defensive tries to the end of the variation.

I hope you are enjoying this article! If you’d like to explore many more similar chess lessons, do visit my personal blog at www.chessinprogress.com, where I’m working on a collection of 100 tactical and strategic articles. While some are posted here on Lichess, the majority—along with insights into chess psychology and my own chess journey—can be found exclusively on my blog. Hope to see you there!

Position 7: Black to play and win

Did you calculate the variation to the end? Including the win of Na4 and that our Bb7 is protected by Na5 (so there is no Re7 in the end of any lines). If so, well done, it is also good calculation training! I hope these examples have shown the importance and abundance of X-rays and indirect contacts. Did you like the puzzles? Was there any that gave you a bit more trouble than the others? Let me know in the comments, I’d love to hear which one caught you by surprise.

X-rays attacks - Final Scan

X-ray tactics remind us that not all threats are visible on first glance. They show that indirect contact is something we can absolutely use to our advantage. Keep in mind that anything within our pieces' line of sight, even indirectly, lurks in the position, and it will become a powerful tool in your games if you spot them before your opponents.
In this article we’ve focused on how X-rays create tactical chances. In part 2 (X-Ray Defence: Hidden Resource, Sudden Lifeline) I explore how the X-ray theme can act as a defensive resource, subtly holding positions together when nothing else seems up to the task. In the meantime I will give you here some recommended lessons that build on similar tactical themes to the X-ray:

The Elegant Crosspin
Hidden Moves on Empty Squares

Until then, happy scanning!

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