Chess/The Endgame/King and Rook vs. King

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a b c d e f g h
8a8 black kingb8 black kingc8 black kingd8 black kinge8 black kingf8 black kingg8 black kingh8 black king8
7a7 black kingb7 black kingc7 black kingd7 black kinge7 black kingf7 black kingg7 black kingh7 black king7
6a6 black kingb6 black kingc6 black kingd6 black kinge6 black kingf6 black kingg6 black kingh6 black king6
5a5 black kingb5 black kingc5 black kingd5 black kinge5 black kingf5 black kingg5 black kingh5 black king5
4a4 black kingb4 black kingc4 black kingd4 black kinge4 black kingf4 black kingg4 black kingh4 black king4
3a3 black kingb3 black kingc3 black kingd3 black kinge3 black kingf3 black kingg3 black kingh3 black king3
2a2 black kingb2 black kingc2 black kingd2 black kinge2 black kingf2 black kingg2 black kingh2 black king2
1a1 white rookb1 white kingc1 black kingd1 black kinge1 black kingf1 black kingg1 black kingh1 black king1
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Sample starting position for K+R vs. K mate

This mate takes longer to do than king and queen vs. king, because the king and rook have to work together to trap the opposing king on the edge (often in the corner). The most commonly taught technique involves confining the opposing king into a box using the rook, which is protected by its own king. Then, the box becomes smaller and smaller until the king is forced into the corner. From the diagram on the right:

1.Kc2 Ke5 2.Kd3 Kd5 3.Ra4 Ke5

After the king's position is improved, the box can be constructed:

4.Rd4

The box is d8-d4-h4.

a b c d e f g h
8a8 black kingb8 black kingc8 black kingd8 black kinge8 black kingf8 black kingg8 black kingh8 black king8
7a7 black kingb7 black kingc7 black kingd7 black kinge7 black kingf7 black kingg7 black kingh7 black king7
6a6 black kingb6 black kingc6 black kingd6 black kinge6 black kingf6 black kingg6 black kingh6 black king6
5a5 black kingb5 black kingc5 black kingd5 black kinge5 black kingf5 black kingg5 black kingh5 black king5
4a4 black kingb4 black kingc4 black kingd4 black kinge4 white rookf4 black kingg4 black kingh4 black king4
3a3 black kingb3 black kingc3 black kingd3 white kinge3 black kingf3 black kingg3 black kingh3 black king3
2a2 black kingb2 black kingc2 black kingd2 black kinge2 black kingf2 black kingg2 black kingh2 black king2
1a1 black kingb1 black kingc1 black kingd1 black kinge1 black kingf1 black kingg1 black kingh1 black king1
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Position after 5.Re4

4...Kf5 5.Re4 (see diagram)

Now it's e8-e4-h4.

5...Kf6 6.Kd4

The box can't be reduced immediately, so the king creeps closer.

6...Kf5 7.Kd5 Kf6

7...Kg5 8.Ke6 Kg6 9.Rf4 Kg5 10.Ke5 Kg6 11.Rf5 Kg7 12.Rf6 Kg8 13.Kf5 Kg7 14.Kg5 Kh7 15.Rg6 Kh8 16.Kf6 Kh7 17.Kf7 Kh8 18.Rh6# is similar.

8.Re5

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8a8 black kingb8 black kingc8 black kingd8 black kinge8 black kingf8 black kingg8 black kingh8 black king8
7a7 black kingb7 black kingc7 black kingd7 black kinge7 black kingf7 white kingg7 black kingh7 black king7
6a6 black kingb6 black kingc6 black kingd6 black kinge6 black kingf6 black kingg6 white rookh6 black king6
5a5 black kingb5 black kingc5 black kingd5 black kinge5 black kingf5 black kingg5 black kingh5 black king5
4a4 black kingb4 black kingc4 black kingd4 black kinge4 black kingf4 black kingg4 black kingh4 black king4
3a3 black kingb3 black kingc3 black kingd3 black kinge3 black kingf3 black kingg3 black kingh3 black king3
2a2 black kingb2 black kingc2 black kingd2 black kinge2 black kingf2 black kingg2 black kingh2 black king2
1a1 black kingb1 black kingc1 black kingd1 black kinge1 black kingf1 black kingg1 black kingh1 black king1
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Position after 15.Kf7

Back to shrinking the box: the process repeats itself. Notice that just as in K+Q vs. K, no checks are necessary until the actual mate.

8...Kf7 9.Re6 Kg7 10.Ke5 Kf7 11.Kf5 Kg7 12.Rf6 Kh7 13.Rg6 Kh8 14.Kf6 Kh7 15.Kf7 (see diagram)

Something important to know: if it somehow transpires that White reaches this position but it's his turn to move, all he has to do is move the rook anywhere along the sixth rank (except Rh6+ of course!). Then, Black's king is forced to move to h8, and White gives checkmate with Rh6#.

15...Kh8 16.Rh6#.
The alternative method is based on the opposition of the kings (see below) with the rook being far away. From the same starting position as before:

1.Kc2 Ke5 2.Kd3 Kd5

Once again, White must improve the position of his king first. Now, once the kings are in opposition, he checks along the fifth rank to push the black king back.

a b c d e f g h
8a8 black kingb8 black kingc8 black kingd8 black kinge8 black kingf8 black kingg8 black kingh8 black king8
7a7 black kingb7 black kingc7 black kingd7 black kinge7 black kingf7 black kingg7 black kingh7 black king7
6a6 black kingb6 black kingc6 black kingd6 black kinge6 black kingf6 black kingg6 black kingh6 black king6
5a5 black kingb5 black kingc5 black kingd5 black kinge5 black kingf5 black kingg5 black kingh5 black king5
4a4 black kingb4 black kingc4 black kingd4 black kinge4 black kingf4 black kingg4 black kingh4 black king4
3a3 black kingb3 black kingc3 black kingd3 white kinge3 black kingf3 black kingg3 black kingh3 black king3
2a2 black kingb2 black kingc2 black kingd2 black kinge2 black kingf2 black kingg2 black kingh2 black king2
1a1 white rookb1 black kingc1 black kingd1 black kinge1 black kingf1 black kingg1 black kingh1 black king1
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Position after 2...Kd5

3.Ra5+ (see diagram)

Black has no choice but to give ground.

3...Kc6 4.Kd4 Kb6

4...Kd6 5.Ra6+ immediately cuts Black off the sixth rank.

5.Rg5 Kc6 6.Rh5 Kd6

6...Kb6 7.Kc4 Kc6 8.Rh6+ is the same sort of thing.

7.Rh6+ Ke7 8.Kd5 Kf7 9.Ke5 Kg7 10.Rb6 Kf7 11.Ra6 Ke7 12.Ra7+ Kd8 13.Ke6 Kc8 14.Kd6 Kb8 15.Rg7 Kc8 16.Rh7 Kb8 17.Kc6 Ka8 18.Kb6 Kb8 19.Rh8#.

Using either method, it should take about 15-20 moves to deliver the mate. Theoretically, it should take no longer than 16 moves to checkmate, but depending on the position, one might have to use a mixture of the two techniques to do this.