If you're stuck with your king on the back rank and you're fighting against a pawn and a rook, it may help to know if the back rank defence is going to work for you.
Odds are 50 -50 (depending on the pawn).
The back rank defence only works with the rook's and knight's pawn.
In this example black is defending. He's happy to have his rook on the eighth file and his king in front of the pawn. He's even more happy the pawn is a knight's pawn.
The defence of this position consists of three elements.
- You can alternate your rook between b8 and c8. That way you'll never be in zugzwang.
- If white plays his pawn, you'll check the king from the side. He'll have no good shelter.
- You'll keep your king tucked away in the corner (never leave the corner...).
That's why white's only try doesn't work.
1. Rg7+, Kh8!; 2.Rh7+ Kg8; this is a draw.
Did I already say never leave the corner?
Let's see what happens if you do leave the corner....
After 1. Rg7+, Kf8??;
2.Kh7! threatens to win the black rook.
Now a rook exchange favours white, as the endgame after 2...Rd8; 3.Rg8+, Ke7; 4. Rxd8, Kxd8; is clearly winning for white.
And if black tries to give checks from behind with 2....Rb1; it's too late. White plays 3. Rf7+, Ke8; 4.Kg8, reaching a Lucena position which is winning.
That's why I said don't leave the corner... If you leave the corner, you'll probably loose....
Let's examine them. The rook's pawn works much the same as the knight's pawn. Keep your king tucked away in the corner and you'll be safe.
Unfortunately this isn't going to work with the other pawns.
You can check the example below (the bishop's pawn). The same motifs are present when you use a center pawn instead.
Think about it for a while. What would you play if you're white?
1.Rh7! (threatening Rh8 mate)
Now 1...Ke8; loses the rook to 2. Kh8+ therefore black must play
This allows 2. f7+, Kf8; 3.Rh8+, winning the rook and the game.
No defence possible.
That's all you need to know about the rook back rank defence. Hope this helps.