Two bishops: the edge isn't enough — herd the king to a corner

From Chess Fundamentals by José Raúl Capablanca (1921), Chapter 1 — First Principles, Example 3 (Two Bishops and King against King) · Beginner · about 5 minutes.

Two bishops side by side form a diagonal wall no king can cross. But unlike the rook mate, driving the king to the edge doesn't finish the job here: the mate only exists in a corner, and the attacking king must reach one of a handful of exact squares first (here h6 or g6). This is the ending that teaches patience — and the bishops' special gift for losing a move without loosening the net.

Starting position (FEN): 7k/8/8/8/8/8/8/2B1KB2 w - - 0 1

The line

• 1. Bd3 — The bishops begin by claiming two long diagonals. The cornered king already has very few squares.
• 1... Kg7
• 2. Bg5 — The second bishop joins in.
• 2... Kf7
• 3. Bf5 — The pair now walls off a triangle around the corner — the black king cannot cross either diagonal.
• 3... Kg7
• 4. Kf2 — The bishops can't finish alone. The king starts its long walk toward h6 — one of the squares it MUST occupy before mate is possible.
• 4... Kf7
• 5. Kg3
• 5... Kg7
• 6. Kh4
• 6... Kf7
• 7. Kh5
• 7... Kg7
• 8. Bg6 — The wall advances one square, shrinking the pen to the corner squares only.
• 8... Kg8
• 9. Kh6 — The king reaches its mating post.
• 9... Kf8
• 10. Bh5 — Marking time. Bishops are perfect tempo-losers: the position is unchanged but now Black must step backward. This is the move beginners can't find.
• 10... Kg8
• 11. Be7 — The dark-squared bishop takes f8 away.
• 11... Kh8
• 12. Bg4 — Repositioning: the light bishop heads for e6, from where it will give check on the g8–a2 diagonal the moment the king returns to g8.
• 12... Kg8
• 13. Be6+ — The check that forces the king into the mating corner.
• 13... Kh8
• 14. Bf6# — Fourteen moves. Every mate in this ending looks exactly like this: king adjacent, one bishop checking, the other sealing the diagonal escape.

Takeaway

With two bishops: wall, walk, corner, tempo-move, mate. Remember the two traps — the edge alone is not mateable, and a careless wall move near the end is stalemate. If your bishops ever stop covering adjacent diagonals, the king escapes through the seam.

Play this lesson move by move on the interactive board at https://www.brilliantknight.com/lessons/chess-fundamentals-first-principles/two-bishops-herd-the-king-to-a-corner · All lessons