When you penetrate your opponent's position by sliding a rook down a file toward the enemy king your opponent is facing a rook invasion. An invading rook can often win a game single-handedly, and it can often draw an otherwise lost game.
Rooks need open files. So, always search for ways to open files for your rooks (even if you have to sacrifice material to do it). Also, keep your oponent from doing the same!
First of all, you'll need to know what to do when you have an invading rook. Look for the patterns in the diagram below.
Two Diagrams. White to Move and Win in Each.
On the left, White should play 1. Rc7+. Now, whichever square the Black king goes to (a8, b8, a6, or b6), White can play 2. Rxa7## and he wins. On the right, White should play 1. Rg7+. Now, whichever square the Black king goes to (f6, f5, h6, or h5), White can play 2. Rxg5## and he wins. Keep your eye out for this pattern: {your rook}-{enemy king}-{enemy piece}, all in a straight line horizontally or vertically (not diagonally). If you can achieve this pattern safely, you win.
If you are facing a rook invasion, you need to give your king room to maneouver. Here is a general rule of thumb: To be safe from losing to a rook invasion, your king must be inside of, or can quickly get inside of, an empty 2-by-2 group of squares that has no friendly pieces bordering it except on the squares diagonally off the corners. To see what I mean, let's take a look at the next diagram.
Two Diagrams. White to Move in Each.
On the left, the Black king is safe from the rook invasion because he sits in the empty 2 by 2 group of squares, b6-b7-c7-c6, and their are no Black pieces on a6, a7, b8, c8, d7, d6, c5, or b5. When the White rook invades, the Black king should always move so as to stay in his safe 2-by-2 group of squares. Then White won't be able to achieve the type of winning position from the first diagram. In the right half of the diagram, the Black king is not safe and he will lose. The Black king is in two different 2-by-2 groups of squares: h6-h5-g5-g6 and h6-g6-g7-h7, but each of these squares is bordered by a Black pawn. In fact, Black cannot get to a safe 2-by-2 group of squares in time. White can win beginning with 1. Rg6+. Then, if 1. ... Kh5, White wins by playing 2. Rh6+ achieving the winning pattern from the first diagram, and if 1. ... Kh7, then 2. Rh6+ Kg8 (if 2. ... Kg7 then 3. Rh7+ wins) 3. Rh8+ Kg7 4. Rh7+ and White wins again by achieving the winning pattern from the first diagram. Let's practice this some more:
White to Move and Win.
Black would have been fine if he had advanced his pawns to get them away from his king, but now he loses to 1. Rd1+, and now if 1. ... Kc7 or 1. ... Ke7, then White plays 2. Rd7+ and wins by achieving the winning pattern. If 1. ... Kc8, then 2. Rd8+ Kc7 3. Rd7+ wins and if 1. ... Ke8 then 2. Rd8+ Ke7 3. Rd7+ wins.
If you cannot stop an invading rook, then give yourself some breathing room as quickly as possible and hope for a draw. Consider:
Black to Move and Draw.
Black can draw this by advancing his a and b pawns quickly to give his king a safe 2-by-2 group of squares. Play proceeds: 1. ... a5 2. Rc1 b5 3. Rc8+ Kb7, and the Black king will remain safe on the squares a7-a8-b8-b7. The best White can do is perpetually check the Black king, and he should be happy with this draw since he is down so much material.
Let's take a look at some more complicated positions:
Black to Move and Win.
Sordid(2431) vs. Rekursiv(1916), FICS
Here White has a bit more material but his king is poorly placed and Black is poised for a rook invasion. Black should try to open the g-file as quickly as possible. He begins: 1. ... h4, threatening to take on g3. Now, if White doesn't advance his g-pawn and plays something like 2. Rfd1 (hoping to give his king a safe 2-by-2 group of squares), then 2. ... h3 will be devastating since White won't be able to stop the pawn from queening. So, White must try 2. g4. But then Black responds with 2. ... Nxg4+ and he has a winning rook invasion. In the game, play continued: 3. Kf2 Rg2+ 4. Ke1 Re2+ 5. Kd1 Re1+ 6. Kc2 Rc1+ (winning pattern achieved) 7. Kd2 Rxc3##.
Below is another actual game featuring a shocking rook invasion.
White to Move.
Banditos(2086) vs. Seberg(2217), FICS
In this game, White has been eyeing Black's weakness on e7 for some time. He would like to play Ba3, but he can't right now because of Black's response Bxb3. So, White begins 1. c4, threatening 2. Ba3. Black takes stock of the situation and very cooly plays 1. ... dxe3!, setting a trap (as we will see) that takes a lot of foresight. Play continued 2. Ba3 O-O-O, the only non-losing move by Black, and now White falls for the trap: 3. Bxe7??, gobbling up a lot of material. As soon as the dust from that last explosion cleared, I'm sure White felt some regret. Play continued 3. ... Nf6, and now it is apparent: Black has a winning rook invasion. White can't close up the e-file or get out of the way. Castling would just lose to Ng4. Play continued 4. Nc3 Re8+ 5. Ne4 Nxe4+ and White resigned (the ending would have been 6. Kd1 Re1+ 7. Kc2 Rc1+ 8. Kd3 Rxc4##). By the way, 4. d4 (trying to get breathing room) wouldn't have helped: 4. ... Re8+ 5. Kd2 Re2+ and White cannot get to a safe 2-by-2 group of squares, and he will soon lose.
Sometimes rook invasions aren't clear-cut and must be calculated quite deeply. Consider:
White to Move and Win
Here, the nearest safe group of 2-by-2 squares is f4-f5-g5-g4, which is hardly safe, actually, because the White pawns can participate in a mate. So, White should have a win here. But he must make some clever non-checking moves to succeed. Play proceeds: 1. Re8+ Kg7 2. Rg8+ Kf6 3. Rg5! This is a common type of move in rook invasions. It cuts off the Black king from advancing any further and it threatens to achieve the winning pattern with Rf5+. So, Black's next move is forced: 3. ... Ke6 4. Re5+ Kd7 5. Re7+ Kc8. Note that 5. ... Kd8 loses even quicker (it transposes into the main line in a couple moves). Play proceeds: 6. Rc7+ Kd8 7. Rd7+ Kc8 (7. ... Ke8 8. Rd8+ Ke7 9. Rd7+ 1-0) 8. Rd8+ Kb7 9. Rb8+ Kc7 10. Rc8+ 1-0.
In endings like the one above, note that the invading rook wants to move with check as often as possible since any non-check move might allow the opponent to either move a piece forward giving the king some breathing room, or make some other offensive move like moving a pawn closer to queening. Here's another example:
White to Move and Win
Play proceeds: 1. Rc8+ Kd7 2. Rc7+ Ke8 3. Re7+ Kd8 4. Rd7+ Ke8 5. Rd8+ Kf7 6. Rf8+ Kg6 7. Rf5! Kh6 (7. ... Kh7 8. Rf7 1-0) 8. Rh5+ Kg6 9. Rg5+ [1-0].
Another tactic at an invading rook's disposal is attacking pieces next to the enemy king to get them to move or to herd the enemy king in a desired direction. Checks don't always get the job done. Consider:
Black to Move and Win
Black must deal with the threat of Bxb7##. If he plays Qxa6, then he has no hope of winning (only drawing) because at the least, White can make breathing room with f4. So, Black should consider moving his king. It is better to move it to d7 than d8 because on d8, he will be subject to check if White's g-pawn queens. In fact, Kd7 is the only winning move: 1. ... Kd7 2. Bxb7 Rd1+ 3. Kg2 (not 3. Ke2 Rd2+) 3. ... Rf1!. This is the key move as 3. ... Rg1+ would allow White's king to escape with Kf3. Now not only is Kf3 not an option, but moving the f-pawn isn't either because of Rf2+. Play proceeds: 4. Kh3 Rg1 5. g7 (5. Kh4 loses to 5. ... Rg4+ etc., with a winning rook invasion). Play proceeds: 5. ... Rg4! 6. g8=Q Rh4+ [0-1]. Black is glad his king didn't move to d8!
This next example shows a common pattern of {enemy pawn}-{enemy king}-{your rook}, all in a diagonal line such as on a6-b5-c4. In such a position, the enemy king cannot move without your rook then achieving the winning pattern.
Black to Move and Win
Play proceeds: 1. ... Rc4! (the key pattern). Now White is forced to move his pawn (if he didn't have this pawn he'd lose immediately) since Ka5 loses to Ra4+ (and if Kb6 were legal, it would lose to Rc6+). Play proceeds: 2. d3 Kh2 3. d4 Kh1 4. d5 Rb4+!. Now that the d-pawn has advanced closer to the White king, Black has some tactical possibilities. Play proceeds: 5. Kc6 Rb7!. This is the key pattern again, and this time, White has no useful waiting moves: d6 loses to Rb6+, Kc5 loses to Rb5+, and Kd6 loses to Rd7+.
Sometimes an invading rook can't get the job done alone, but a second rook can get into the action. It goes without saying that two rooks can easily create a deadly attack, because not only can an explosion be forced by the winning {rook}-{enemy king}-{enemy piece} pattern, but the two rooks can force a mate (often a back-rank mate). Consider:
Black to Move and Win
Rekursiv vs. tipau, FICS
Black would like to get its king rook in play, but his king is blocking it, and right now Ke7 would be met with white playing a rook to e1, and Kc7 would be met with Rc1 pinning the Black rook and trading. So, Black does a little prep work first: 1. ... Ra2+ 2. Kb1 Ra1+ 3. Kb2 Kc7!. Now White cannot play Rc1+, and Black's other rook will be decisive. Play proceeds: 4. Bg2 d5 5. Kc3 Ra3+ 6. Kb2 Rb8+ [0-1] and now the win is easy.
Let's look at another double-rook attack, but this one happens one rook at a time.
White to Move and Win
siggemannen vs. Rekursiv, FICS
Here, White will attack the Black king first with one rook, and then with the other. Play proceeds: 1. Rd7!. White is threatening a winning rook invasion, and Black must accept the sacrifice with Nxd6 since 1. ... Ke6 is met by 2. Re7+, 1. ... g6 is met by 2. Rf7+ Ke6 3. Re7+, and 1. ... Kf5 is met by 2. Rf7+ Ke6 3. Re7+ too. So, play proceeds: 1. ... Nxd6 2. Rc7!. Excellent move as 2. Rc6+ would give the Black king breathing room: Ke7. Now the remaining White rook wins just as the first White rook was threatening to (2. ... Ke6 3. Re7+ [1-0], 2. ... Kf5 3. Rf7+ Ke6 4. Re7+ [1-0], 2. ... g6 3. Rf7+ Ke6 4. Re7+ [1-0]).
Sometimes, one rook takes a pawn to open a file, and the other rook occupies the file. Consider:
White to Move
yokke vs. Rekursiv, FICS
Here, Black is threatening Rxb3. Unless you are used to this, this rook takes pawn tactic can come as a rude awakening. Here, White has some winning chances (with a bishop and pawn for a rook) and probably should play 1. Rb1 to defend, but makes this choice instead: 1. c5?! Rxb3! 2. Bb5 axb5 3. Rh1 and a draw was agreed. If White had played 1. Rb1 instead, then he would have held onto some winning chances without danger of losing.
In the next example, Black combines threats of a winning rook invasion and winning material to win the game.
Black to Move and Win
In this position, White's king is on the safe group of squares h1-g1-g2-h2, so Black will have to make other threats besides a straightforward rook invasion. Black's surprising plan hinges around attacking the pawn on h5, threatening to win the White rook, and if the White rook moves down away from the h5 pawn to avoid being exploded, then suddenly White's king won't have enough breathing room and he will succumb to a rook invasion. However, it will take two moves for the Black rook to get into attack position. So, White will have some tries to extricate himself. Play proceeds: 1. ... Rd2!. Now let's see what will happen if White waits around for Black to attack h5: 2. Kg1 Rd5! and now if 3. Rh3 then Black has a winning rook invasion with 3. ... Rd1+ 4. Kg2 Rg1+ etc. Also fruitless is 3. Rxf4 Rd3 4. Kf1 Rxb3 etc. So, after 1. ... Rd2 White has to try something other than a king move. Since Rh3 loses to Rd1+ and Rxf4 loses to Rd3 then Rxb3 as above, White's only other try is 2. Rg4, but then Black has 2. ... Rh2+! 3. Kg1 Rxh5 and his extra pawn will win (see endgame section).
Of course, there are all sorts of defenses to rook invasions. Besides giving yourself breathing room, you can try to prevent them from happening in the first place by blocking open files with pieces. Here is an example:
White to Move
Rekursiv vs. Francisko
Here, Black is threatening to open the g-file for his rook with Nxg3. White can't prevent this move, so he looks around to find a piece he can use to block the file. Ah, the bishop! Play proceeds: 1. e4!. Now, if 1. ... Nxg3+, then 2. Bg5. Now White is safe and his material advantage won him the game. Play proceeds: 2. ... Ke8 3. Rf3 (Kh1 is good too) fxg5 4. Rg3 Kd7 5. Rf1 and White won.
Sometimes rook invasion threats and defenses can ebb and flow for some time before the outcome is decided. Consider:
White to Move
Rekursiv vs. Sordid
Here, White has sacrificed a lot of material to achieve some rook invasion possibilities. White's pawns on d4 and f4 facing Black's pawn on e6 are in a common tactical position where White's f-pawn can advance to attack the e6-pawn, and if that e-pawn advances, White's d-pawn is waiting to capture it. This is a typical way to open a file. Play begins: 1. f5 Na6 2. O-O. White ignores the Black knight and prepares a rook to occupy the soon-to-be-opened e-file. White plans to allow the Black knight to capture on c2, opening up more room for his rooks.
Play continued: 2. ... Nb4 3. a3 Nxc2 4. Rae1. Note that 4. Rfe1? allows Black a defense: 4. ... d5! 5. fxe6+ Be6 and Black will win. With 4. Rae1 this defense doesn't work: 4. ... d5 5. fxe6+ Be6 6. Rxf6+! 1-0. Play proceded: 4. ... Bb4 (an important move to guard the e8-square with the h8-rook from a future rook invader) 5. axb4 Kd8. Here, 5. ... O-O would have lost to 6. fxe6 Re8 7. Re7 Rxe7 8. Re1 g5 9. Re8+ etc. Play continued: 6. fxe6 Kc7 7. b4. If 7. Re7 or 7. Rc1, then 7. ... Kb8, and the attack would probably run out of gas and Black would come out on top. With 7. b4, White has achieved the tactical pawn position required to open the c-file.
Play continued: 7. ... a5 (planning on getting the rook on a8 in play for some defense) 8. b5 Kb8 9. bxc6. Now, White's two rooks are looking dangerous and Black's king precarious. Play continued: 9. ... Ra6. This is a "rook lift" where the rook of the defensive side comes forward a couple of files so that it can swing left and right to block invading rooks. Play continued: 10. Rb1 Rb6 11. Rb5. Note that 11. Rxb6 let's Black escape with 11. ... Kc7! (any other move allows White to win with a rook invasion on the c-file. After 11. ... Kc7! 12. Rc1+ Kd6, I don't think there is a White win and White has to be careful to draw. White cannot let Black connect kings for example, because then Black's material advantage would easily win. For example: 13. Rc6+ Kd5 14. Rc5+ Ke4 15. Rf5 draw, or 13. Rc5 Ke7 14. Rc1 Kd6 draw.
Play continued: 11. ... Ka8 12. Rxa5?? White finally throws away half a point. He could have won with 12. Rc1! after which there is no stopping 13. Rc7. For example: 12. Rc1! Rxb5 13. Rc7 b5 14. Ra7+ Kb8 15. Ra8+ 1-0. Play continued: 12. ... b6! 13. Rc1 (13. Ra1+ Ba6) Re8! 14. Rc7 Re2 and the game soon ended in a draw.
Sometimes an invading rook has other goals besides mating the enemy king or getting a draw by perpetual check. Another common tactic involves a White rook, say, that penetrates to the 8th rank with check. Then the enemy king steps to the 7th rank, and the White rook then checks on the 7th rank, after which the White rook takes something on the 7th rank for a material advantage. I call this a "rook sweep." There are all sorts of variations of this. Consider:
White to Move and Win.
Play proceeds: 1. Re8+ Kf7 2. Re7+ Kf8 3. Rxb7, and White's extra pawn is decisive (see Endgame section).
Sometimes a rook sweep doesn't involve the enemy king at all. For example:
Black to Move.
Here, Black can play 1. ... Rc2. This is a threat to take on b2 winning a pawn. Since there is nowhere for the White rook to safely run to, and moving the b-pawn just gives Black the opportunity to win the a-pawn, Black will win a pawn and probably the game.