Last week we analyzed bishop endgames where a king played a major role. We studied a pattern where the bishop sacrifice cleared the way for the king. Today we will continue with the topic of king activity in bishop endgames but will look at different ideas. We will not be able to cover all of the ideas associated with king activity but concentrate on a few important ones. The first two examples will feature bishop sacrifice from a defensive point of view. The other examples will include the themes of pawn breakthrough and king's entrance into the opponent's position through the squares of the same and opposite color of the bishop.
The strategy explained in the next two examples works for positions where there is a passed pawn on one side but where the defending side has a majority on the other side. The defending side can try to stop the passed pawn but it will take time and resources, where the attacking side can use the deflected defender's pieces to run with the king to the other flank and collect pawns there. Or the defending side can sacrifice the bishop for the passed pawn but come with the king to the other flank where the attacking side has a pawn minority.
In the first example, the b5-pawn looks impressive, however the d-pawn can potentially move forward and create a passed e-pawn. Black takes the correct decision and eliminates the b-pawn right away; in return he gets a passed pawn and active king. Notice how all the white pawns on the kingside are on the opposite color squares from the bishop, so when the king comes up to collect them the bishop can only watch.
Below, the scenario is similar to the first example. White has the king supporting the passed pawn on the kingside, while black has the king in the centre and potential passed d-pawn. The h-pawn is far advanced and black has little choice but sacrificing the bishop for it. The complications arise when black is trying to get into white's position with the king. White's bishop and the c3-pawn cover the entrance squares, so black has to be precise in his implementation.
The defending side should aim to keep many pieces on the board when the attacking side's king is active. This is so because with less pieces on the board the significance of the king activity increases. Take for example, the next position. The knight on d8 is not the most active piece but it defends the key c6-pawn thus black must not trade the knight but instead rely on tactics to preserve it.
In the next two examples white's active king invades the black position because the pawn structure is fixed and black cannot cover all the weak entrance squares. In the first position black loses the kingside pawns but gets the passed d-pawn. White is ready to sacrifice the bishop for the pawn and to get three passed pawns for the bishop. Because the black king is far away, the bishop cannot stop all three of them. To get to the bishop endgame white had to exchange the bishop for the knight first - a similar idea from the previous example.
The last example features an active king for white and a "bad bishop" for black. The bishop is locked behind the f6-pawn. First, white improves the king position and then temporarily sacrifices a pawn (or even two pawns in some variations) to get the king in. White would not be able to win this endgame without a zugzwang idea. The bishop on g7 defends the f6-pawn and can do so only from the g7 or the h8-square. The king has to stay on b7 because it guards the c6-square. On the other hand, the white bishop can freely move on the a3-f8 diagonal winning tempos to put black into a zugzwang.
In summary we looked at positions where king activity plays a key role in bishop endgames. We covered a combination of ideas including bishop sacrifice from the defensive point of view, pawn breaks and exchanges that lead to the bishop endgame. On this note we are wrapping up bishop endgames and moving on to endgames where many pieces are present.