Decide
Step 1 · Where does the king’s bishop belong?
White to move
rnbqkb1r/ppp2ppp/4pn2/3p4/3P1B2/4P3/PPP2PPP/RN1QKBNR w KQkq - 0 4Your queen’s bishop is out and e3 is played. The other bishop is still at home.
Where does the f1 bishop belong in the London?
Quick check
- d3, on the b1–h7 diagonal
- e2, behind the pawns
- b5, pinning the knight
Show the correct answer
Correct answer: d3, on the b1–h7 diagonal — d3. The bishop looks straight at h7, the square next to where Black will castle. Everything else in the London is built around this diagonal.
- e2, behind the pawns — e2 is safe but looks at nothing. The engine calls it equal, and it is; the London bishop belongs on d3, where it works.
- b5, pinning the knight — There is nothing to pin: no knight on c6 yet, and …c6 chases the bishop with tempo. d3 is the working square.
Watch
Step 2 · Everything aimed at one corner
White to move
r1bq1rk1/pp3ppp/2n1pn2/2pp4/3P4/2PBPNb1/PP1N1PPP/R2QK2R w KQ - 0 9Black traded bishops: …Bxg3, and hxg3 opens the h-file for your rook. After 9…Qe7 10.Ne5, the bishop on d3 and the rook on h1 both look at h7, and the queen can come to h5. One piece still guards it: the knight on f6.
The line: 9.h2xg3 Qd8-e7 10.Nf3-e5
Your move
Step 3 · Not yet
White to move
r1b2rk1/pp2qppp/2n1pn2/2pp4/3P4/2PBPNP1/PP1N1PP1/R2QK2R w KQ - 1 10The bishop is aimed and the h-file is open. Is it time? Choose White’s move.
Hint: Ask the two questions first: who guards h7, and can the king take on h7? Then choose the building move that keeps everything aimed.
The move: 10.Nf3-e5
10.Ne5. You kept building: the knight eyes g4 and d7, and Black now has to do something about it. The sacrifice waits for the knight on f6 to move.
Why not another move?
10.Bd3xh7— The knight on f6 simply takes: …Nxh7, and you have given a bishop for a pawn. Undo. While a knight guards h7 the sacrifice is a loss. What follows:10…Nf6xh710.O-O— Castling is safe, but it lets Black untangle with …e5 or …h6. Ne5 keeps every piece aimed and forces …g6. Undo and play it.10.Qd1-e2— A quiet move, but it gives Black time. Ne5 keeps every piece aimed at the corner and forces …g6. Undo.10.e3-e4— A good central break in its own right. The lesson’s move is Ne5, which keeps the attack aimed and forces …g6. Undo.
Watch
Step 4 · The guard leaves
Black to move
r1b2rk1/pp2qppp/2n1pn2/2ppN3/3P4/2PBP1P1/PP1N1PP1/R2QK2R b KQ - 2 10Black challenges your knight: 10…Nd7. Natural, and a mistake. The only piece that guarded h7 has just walked away from f6.
The reply: 10…Nf6-d7
Play the line
Step 5 · Cash in
White to move
r1b2rk1/pp1nqppp/2n1p3/2ppN3/3P4/2PBP1P1/PP1N1PP1/R2QK2R w KQ - 3 11Now both answers are yes: no knight on f6, and the h-file is open behind your bishop, so the king cannot even take it. Five checks in a row. Start with the bishop.
The line: 11.Bd3xh7 Kg8-h8 12.Bh7-g6 Kh8-g8 13.Rh1-h8 Kg8xh8 14.Qd1-h5 Kh8-g8 15.Qh5-h7
Hint: Follow the pattern: bishop check on h7, a second bishop check that unmasks the rook, rook to h8, then the queen.
Move by move
11.Bd3xh7 Kg8-h8— Bishop takes h7 with check. The rook on h1 means the king cannot take it back; it has to hide on h8.12.Bh7-g6 Kh8-g8— Move the bishop again with check: the rook on h1 is unmasked. g6 keeps f7 under fire too.13.Rh1-h8 Kg8xh8— Rook to h8, with check. The king has to take it.14.Qd1-h5 Kh8-g8— Queen to h5, with check. The king has only g8.15.Qh5-h7— Queen to h7. Checkmate: the bishop on g6 protects the queen.
Checkmate. Five checks in a row, because the guard had left f6 and the h-file was open behind the bishop.
Why not another move?
11.Ne5xc6— Nxc6 wins material too, but the sacrifice on h7 is mate. Look at h7 first.11.Qd1-h5— Played first, Qh5 keeps a strong attack, but …h6 holds and there is no mate: the forced mate starts with the bishop on h7. After the two bishop checks Qh5 also forces mate, because your knight on e5 covers f7, but this line puts the rook before the queen: Rh8+. Undo.12.Bh7-c2— Bc2+ also wins: any discovered check from the rook does. This line follows Bg6+, which keeps f7 under attack as well.12.Bh7-d3— Bd3+ also wins: any discovered check from the rook does. This line follows Bg6+, which keeps f7 under attack as well.12.Bh7-e4— Be4+ also wins: any discovered check from the rook does. This line follows Bg6+, which keeps f7 under attack as well.12.Bh7-f5— Bf5+ also wins: any discovered check from the rook does. This line follows Bg6+, which keeps f7 under attack as well.
Decide
Step 6 · Why did it work this time?
White to move
r1b2rk1/pp1nqppp/2n1p3/2ppN3/3P4/2PBP1P1/PP1N1PP1/R2QK2R w KQ - 3 11One move earlier the same sacrifice lost a bishop.
What made 11.Bxh7+ work now?
Quick check
- The knight had left f6 and the h-file was open behind the bishop
- The bishop was aimed at h7
- Black’s queen was on e7
Show the correct answer
Correct answer: The knight had left f6 and the h-file was open behind the bishop — Both. Without the knight nothing recaptures on h7, and with the h-file open the king cannot take the bishop either, because the rook on h1 covers it. Check both every time.
- The bishop was aimed at h7 — It was aimed one move earlier too, and then the sacrifice lost a piece. Aim is the precondition; the missing guard and the open file are what made it win.
- Black’s queen was on e7 — The queen on e7 changed nothing about h7. What changed was the knight leaving f6 and the h-file being open.
On your own
Step 7 · On your own
White to move
r1bq1rk1/p4ppp/1pnbpn2/2pp4/3P4/2PBPNB1/PP1N1PPP/R2QK2R w KQ - 0 9A different London game. Your bishop points at h7, Black has castled and just played …b6. Choose your move.
Hint: Ask the two questions. A knight on f6 answers the first one for you: not now. So build.
The move: 9.e3-e4
9.e4. You opened the centre while the sacrifice was not on: the knight on f6 still guards h7. Keep building; the diagonal stays loaded.
Also good here
9.O-O— Castling is fine: the sacrifice is off while the knight guards h7, so a building move is right. The strongest one is e4, opening the centre.9.Qd1-e2— A good building move that also prepares e4. The strongest is e4 at once.9.a2-a3— Quiet and playable. Stronger: open the centre with e4 while the sacrifice is off.
Why not another move?
9.Bd3xh7— …Nxh7. The knight was still on f6, so the bishop is simply lost. Undo. Aimed is not the same as ready. What follows:9…Nf6xh79.Nf3-e5— Ne5 is playable, but here Black just trades on e5 and the pressure is gone. Open the centre with e4 while the sacrifice is off. Undo.9.h2-h3— h3 wastes a move and invites …Bxg3, when fxg3 wrecks your pawns. Undo and open the centre with e4.
A quick refresher
In the app this position is not part of the lesson itself: it comes back later, as a review, to check that the idea stuck.
Play the line
The guard has gone again
White to move
r1b2rk1/pp1nqppp/4p3/2ppP3/8/2PBP1P1/PP1N1PP1/R2QK2R w KQ - 1 12Black took your knight on e5 and you recaptured with the pawn; then …Nd7. Two questions, then act. One thing has changed: no knight of yours covers f7 now.
The line: 12.Bd3xh7 Kg8-h8 13.Bh7-g6 Kh8-g8 14.Rh1-h8 Kg8xh8 15.Qd1-h5 Kh8-g8 16.Qh5-h7
Hint: Bishop check on h7 first; then a discovered check with the bishop; then the rook to h8 before the queen.
Move by move
12.Bd3xh7 Kg8-h8— No knight on f6 and the h-file is open: the bishop goes first.13.Bh7-g6 Kh8-g8— A second bishop check unmasks the rook.14.Rh1-h8 Kg8xh8— Rook to h8 with check. Here the rook must go before the queen.15.Qd1-h5 Kh8-g8— Queen to h5, with check.16.Qh5-h7— Queen to h7. Mate.
Checkmate, from a different move order. The pattern is the same five checks whenever the two conditions hold.
Why not another move?
12.Qd1-h5— Qh5? Played first, …h6 holds. After the two bishop checks, …fxg6 answers it and the king escapes by f7: no knight of yours covers f7. Undo. The rook goes to h8 first, with check.13.Bh7-c2— Bc2+ also wins. This line follows Bg6+.13.Bh7-d3— Bd3+ also wins. This line follows Bg6+.13.Bh7-e4— Be4+ also wins. This line follows Bg6+.13.Bh7-f5— Bf5+ also wins. This line follows Bg6+.
What you learned
Bishop to d3 loads the b1–h7 diagonal. Cash it in only when the h7 guard has left and the rook backs the bishop down the h-file; until then, keep building.
In your next game
In your next London game: bishop to d3 early. Before any Bxh7+, ask two questions: is a knight still on f6, and is the h-file open behind the bishop so the king cannot take it? Two yeses, and the sacrifice wins. One no, and it just loses a bishop.