Weekly Endgame Column #2

Troitzky, from his treatment of the endgame 2N vs. pawns: White to move and win. You are welcome to try and solve the exercise before reading on.

This week: introduction to the endgame 2N vs. pawn. We shall learn two basic steps: 1) change the front and 2) release the reserve knight to attack and mate the king.

This is probably the most difficult endgame there is, and understanding it is a great satisfaction. Which is why I treat it in my Endgame Column. There are several benefits from working with this endgame:

  • Learn to coordinate 3 relatively weak pieces (K+2N).
  • 2 knights are no better than losing a tempo than 1! King triangulations are relevant, and thus it is a follow-up on last week’s Endgame Column (#1).
  • It is instructive to see how king + 1 knight can control the Black king – as the reserve knight has to block the pawn.
  • The positions are tempo-sensitive and needs precise planning, until the reserve knight can be released to deliver mate.

Our investigation begins where the Black king has already been trapped in one of the 4 corners. This is the case in all positions this week. The most complicated task in the endgame 2N vs. pawn is to force the Black king around the board with only K+N, as the reserve knight has to block the pawn.

All positions with solutions can be found at the end of this article, in playable format.

1. Change Front

White to move. To change front means that White’s king and knight are transferred to f7 and f5 in this position – with the Black king on h7. White uses the square diagonal to the corner (here g7) for the knight transfer.

1.Kf6

Because of the knight controlling f8 and g7, White is able to lose a tempo – and thus it is always possible to change front from the outset.

1…Kh7 2.Kg5 Kh8 3.Kh6! Kg8 4.Kg6

We have reached the starting position with Black to move.

4…Kh8 5.Kf7 Kh7 6.Ng7!

By using the g7–square (covering h5), the Black king is still kept in the h8–corner.

6…Kh6 7.Kf6 Kh7 8.Nf5 Kg8 9.Ke7

In this position, it is worth noting that the position of Kf7–Kh7 with White to move is not possible if Black decides so. This little fact has bearing on the Troitzky Line (which I will explain in a later Column).

9…Kh7

Forces the White king to f7 to protect g6.

9…Kh8!? This move gives White a choice, and Black usually plays this only to confuse White. Now both 10.Kf8 and 10.Kf7 are possible, depending on the circumstances.

10.Kf7

The changing of front is complete. Here, Black it is to move. Again, if Black so wishes, White is not able to get the move in this position after the changing of fronts.

As a little exercise, I suggest that you change the front back to the starting position, just to get used to the idea. I give the sequence of moves in the solutions at the end of the blog post.

2. Release the reserve knight – the direct mating attack

1. Troitzky: White to move and win. Before White can release the reserve knight on e2, he needs to change front to make sure that the Black king is where he wants it to be – the Black pawn is only 2 squares away from promotion!
2. Troitzky: White to move and win. Against a pawn on f3, it is even trickier, as the pawn could promote with check – or Black might be able to sacrifice the queen on f7. So White has a few obstacles to overcome, besides changing front and finding the right moment to release the reserve knight on f2.

Before we move on, it is worth noting that the pawns on e3 and f3 in the previous examples have both crossed the Troitzky Line. With the Line crossed, White is not able to mate the Black king in all 4 corners on the board – but this is not a problem in the exercises above, as the king is trapped in a corner where the final mating attack is possible.

3. King triangulation

The last 2 exercises show yet more examples of the knight’s inability to lose a tempo. Therefore, the king has to step in.

3. Troitzky: White to move and win. Here, the problem is not releasing the reserve knight – but rather to deal with the annoying d-pawn, once it starts moving down the board.
4. Lund: White to move and win. Again, releasing the g4-knight is not the problem, the g5-pawn and the timing is.

Solutions to the exercises can be found here.

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