11
[FEN "8/8/8/8/3k1KB1/8/8/8 w - - 0 1"]

I am new to chess and have no clue as to how to win this game. Which moves can be done with what is on the board in order to win? Could anyone explain?

  • 19
    Bishop and king versus king is a draw. You cannot checkmate. – B.Swan Nov 30 '20 at 8:38
  • 2
    When you asked this question, was the game still on-going? – Mast Dec 1 '20 at 16:48
  • @Mast It couldn't have been, since any game reaching that position is automatically over. (But since OP didn't know that, it's worth pointing out that it's usually cheating to ask about a game in progress.) – D M Dec 5 '20 at 13:20
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This position is a draw, the game is over. It is not possible for either side to checkmate the other from this position, not even if the side with the bare king would try to help.

The same is true for king and knight vs king. A single knight or bishop without any pawns or other pieces is not enough to win the game.

With king and two knights vs king it is in theory possible to checkmate the other side, but it can't be forced. It's very easy to prevent the checkmate as the defending side. So that is essentially a draw too.

Two bishops, or a bishop and a knight, can force checkmate. It's not easy (especially bishop and knight, it has happened that a grandmaster fails to do it), but it can be done.

It's a better idea to always keep a pawn or two on the board so you can promote one.

  • 1
    I must be missing something. If Black King is at A1, White King is at C1 and White Bishop is in the diagonal above that (say B3) and it's black's move isn't that checkmate? And if not White could move king to C2 and then that'd still be checkmate. – brenzo Nov 30 '20 at 17:05
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    @brenzo that would be stalemate (draw), nothing is attacking the black king – Stephen S Nov 30 '20 at 17:31
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    Just to finish the thought for beginners, a single rook can force a mate (and by extension a queen as well of course). – Flater Dec 1 '20 at 11:11
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If you look closely, the bishop only attacks on squares of a specific color (in this case, it's a light square bishop). As long as the opponent king steps on dark squares, it's impossible to 'check'mate the opponent king. During the endgame with very few pawns on the board, it is most likely best to sacrifice your piece for an opponent's pawn, as they have very big potential of promoting. As said before by @RemcoGerlich, it's a good idea to keep more pawns on the board so you have more potential.

As an example, if you have King + Pawn vs King + Bishop + Pawn, there's no point trying to exchange the pawns, as that would lead to a draw. You can instead take away your opponent's pawn with the bishop, leaving a King vs King + Pawn which hopefully would not lead to a draw.

  • 1
    Definitely not an expert and perhaps this is never necessary with smart play but it seems that depending on the positioning perhaps there is a point to drawing by exchanging the pawns for the player with the bishop if the alternative is a loss due the opponents promoted pawn. – Kvothe Dec 1 '20 at 18:17
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    @Kvothe +1 as I (also inexperienced gos) think you're right, but I think that's a very narrow edge case. You won't often find his pawn so close to promotion that a bishop can't intercept late, AND your pawn is still on that side of it to trade. Unless the trade is made by taking each pawn with a king on opposing sides... idk, like I said, +1 possibility, I think dinosauce still has the generally correct strategy though. – TCooper Dec 1 '20 at 19:29
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    While it's not possible to checkmate with K+B, the reason you give isn't really valid, since it is always possible to force the black king off the dark squares and then give check. The real reason is that when black is in check there is always a dark square available to escape to. – Especially Lime Dec 2 '20 at 9:45
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Generally, when asking how to win a game, you will ask for a particular player. For example, you can ask: How can White win this game? In fact, that seems to be what you are really asking here.

However, this position is a dead position: neither player can achieve checkmate through legal moves, no matter how badly the other player plays. Under FIDE (World Chess Federation) rules, this automatically causes the game to end in a draw [1]. As soon as a player or an arbiter notices this, they should stop the game.

Of course, casual players are free to ignore the previous paragraph. What happens if we try to achieve checkmate in this position? We might get something like:

[FEN "8/8/8/8/8/5B2/8/5K1k w - - 0 1"]

The Black king is in a corner (h1), with only three adjacent squares. One (g2) is controlled by the bishop and one (g1) is controlled by the White king. It can still escape to the other square (h2). We can't do any better than this, so we can never get checkmate.

There are some variations that would allow checkmate. Some have been covered in other answers. One very interesting one that has not been covered is to give Black a pawn. This can actually hurt Black!

[FEN "8/8/8/8/8/5B2/7p/5K1k w - - 0 1"]

To get this position using legal moves, first move the pawn to h3 and the bishop somewhere off the main diagonal. Then move the kings into position. Finally, move the Black pawn to h2, then move the bishop onto the main diagonal, giving checkmate!

[1] Assuming the preceding move was legal and complied with the touch-move rule.

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