[Event "Beginner Endgames You Must Know!: Exercise 3: The crucial rook box position"]
[Site "https://lichess.org/study/wukLYIXj/ldlxdMdS"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[Annotator "https://lichess.org/@/NoseKnowsAll"]
[ECO "?"]
[FEN "8/8/2k5/8/3K4/4R3/8/8 w - - 0 1"]
[Opening "?"]
[SetUp "1"]
[UTCDate "2021.05.24"]
[UTCTime "16:53:15"]
[Variant "Standard"]

{ Black has just played Kc6, trying to stay as central as possible. What maneuver do we need to remember in order to take opposition away from our opponent? [%cal Be3e8,Be3a3] } 1. Ke5 $1 { Nice job! Because the black king wasn't threatening to escape our box, white can cross over this line in order to wrestle away more space from the black king. [%csl Bd6] } ( 1. Kc4 $2 { A good try, but not correct. In this case black can go back with Kd6 and our best move should be to repeat ourselves with Kd4, trying again. We have taken opposition, but in this case our opponent sadly does not need to give ground. } 1... Kd6 2. Kd4 ) ( 1. Re5 $6 { This move definitely makes a lot of sense, but after Kd6 it's us that has to give ground. The rook needs to stay in place to prevent the enemy king from escaping the box, and the white king has to keep protecting the rook. } 1... Kd6 ) ( 1. Re6+ { An excellent move that I didn't show in the previous chapter. After Kd7, we have Kd5 and we have made progress. And after Kb5!? we can play Rd6! and black must again walk into opposition with Kb4 Rb6+, giving further ground. } 1... Kb5 2. Rd6 $1 Kb4 3. Rb6+ Ka5 4. Kc5 ) 1... Kd7 { The best try from black would have been to stay centralized with Kc5, but walking into opposition like that allows Rc3+, and we have successfully shrunk the box. } ( 1... Kc5 2. Rc3+ Kb4 3. Kd4 { The box has shrunk. } ) 2. Kd5 ( 2. Rc3 $1 { The fastest way to mate! This excellent move is one I didn't show in the previous chapter. After Ke7, we have Rc7+ and the king is forced onto the back rank. } 2... Ke7 3. Rc7+ Kd8 4. Kd6 ) 2... Kc7 3. Ke6 { Not the fastest way to win (we should already be thinking about trapping him against the top wall instead of the left wall), but this is the move that we have already discussed. [%csl Bd7] } ( 3. Rb3 $1 { The fastest way to mate! Now Black will again have to walk into opposition and next be forced against the top wall. } 3... Kd7 4. Rb7+ Kc8 5. Kc6 ) ( 3. Re6 $6 { This move definitely makes a lot of sense, but after Kd7 it's us that has to give ground. The rook needs to stay in place to prevent the enemy king from escaping the box, and the white king has to keep protecting the rook. } ) 3... Kc6 4. Rc3+ Kb5 5. Kd5 Kb4 6. Kd4 $18 { And we again have shrunk the box considerably. White is making progress.
Here's Magnus Carlsen pulling this checkmate off in only 5 seconds! https://lichess.org/nPI3zfiw/black#123 } ( 6. Rd3 $1 { The fastest way to mate! Now black will again have to walk into opposition and next be forced against the top wall. } 6... Kb5 7. Rb3+ Ka4 8. Kc4 ) ( 6. Re3 $1 { The fastest way to mate! Now black will again have to walk into opposition and next be forced against the top wall. } 6... Kb5 7. Rb3+ Ka4 8. Kc4 ) ( 6. Rf3 $1 { The fastest way to mate! Now black will again have to walk into opposition and next be forced against the top wall. } 6... Kb5 7. Rb3+ Ka4 8. Kc4 ) ( 6. Rg3 $1 { The fastest way to mate! Now black will again have to walk into opposition and next be forced against the top wall. } 6... Kb5 7. Rb3+ Ka4 8. Kc4 ) ( 6. Rh3 $1 { The fastest way to mate! Now black will again have to walk into opposition and next be forced against the top wall. } 6... Kb5 7. Rb3+ Ka4 8. Kc4 ) ( 6. Rc5 $1 { An equally good move. We have shrunk the box to the bottom left corner and have made considerable progress. Play Kd4 instead to solve this exercise. } ) *