Promotion Play – Part 1

Pawn promotion, as one of the special moves in chess, is a popular device that composers often use as the focus of a problem. Rendering promotion as the theme usually means that the move is set to take place in multiple variations, as a recurring motif. The play may emphasise the need to carefully select the right promoted piece, with underpromotions a favoured feature. Sometimes promotion to a variety of piece types constitutes the main point, as in for instance the Allumwandlung theme, the subject of an earlier Problem World instalment. We will here concentrate on directmates showing this special pawn move, and in the next article examine its appearance in helpmates.

When White gives mate in a problem by promoting a pawn, we need to distinguish only between the choice of queen and knight as the new piece, because the queen encompasses the power of rook and bishop. Problem 85 illustrates how a single pawn can give the maximum six different mates by promoting in turn to a queen and a knight on three squares. The key is 1.Rd7!, which threatens 2.cxb8=S, 2.c8=Q, and 2.cxd8=S. These mates are separately forced in the following lines, in addition to three other promotions: 1…Kxc6 2.cxb8=S, 1….Sxc6 2.cxb8=Q, 1…Kxa7 2.c8=S, 1…Se6 2.c8=Q, 1…Rc8 2.cxd8=S, and 1…Kc8 2.cxd8=Q. In some variations, the queen-promotion mate can be replaced by a rook- or bishop-promotion, but such dual mates are not regarded as a flaw, unlike other cases of non-unique White play.

In Problem 86, Black initially has only two legal moves, and set mates are prepared for them: 1…Kg7 2.f8=Q, and 1…Rxg8 2.fxg8=Q. The diagram is hence a block position, but White lacks a simple waiting move that will maintain the set play. Instead, the key 1.Rxe7! (waiting) changes the white play to a pair of knight promotions: 1…Kg7 2.f8=S, and 1…Rxg8 2.fxg8=S. An added line is 1…Kxe7 f8=Q. This problem exemplifies a class of directmate problems called mutates. In this type, White has set responses provided for all of Black’s moves in the diagram, but after a waiting key, White changes the reply to at least one of these black defences.

If Black promotes in a two-mover, again only the choice of queen or knight is relevant (though in some longer directmates, Black may pick a rook or a bishop in attempting to induce stalemate). Problem 87 uses two black promotions as the thematic defences to generate the Zagoruiko scheme. In the set play, White exploits the self-blocks of the promotion moves by 1…e1=Q 2.Rd4, and 1…e1=S 2.Be3. Virtual play arises after the try 1.Se3? (waiting), giving 1…e1=Q 2.Qc2, and 1…e1=S 2.Sf1, but 1…Bb2! refutes the try by pinning the knight (1…Ba3 2.Se4). The actual play incorporates a third pair of mates in answer to the promotions: 1.Sf2! (waiting), 1…e1=Q 2.Qd3, and 1…e1=S 2.Sfe4. The key grants a flight on e3, and leads to good by-play, 1…Ke3 2.Qd3, 1…Ke1 2.Qxc1, and 1…B-any 2.Sfe4.

In Problem 88, the white rook can threaten mate on the third rank by moving east, but the two black pawns seem capable of defending any of the third-rank squares by promoting to a queen or a knight. To deliver mate in four, White takes advantage of the fact that once a black pawn has promoted to one type of piece, it loses the option to become another one. Consider 1.Rc8? which, if played immediately, is defeated by 1…e1=Q! To preclude this defence, White can force the pawn to promote to a knight instead, with 1.Rd8? e1=S 2.Rc8, but unfortunately 2…f1=Q+! now refutes. Therefore White must take an additional step to induce the f-pawn to promote to the wrong piece as well: 1.Rg8! f1=S 2.Rd8 d1=S 3.Rc8, and now 4.Rc3 is unstoppable. White’s strategy, to counter an adequate promotion defence by provoking Black to promote to a different type of piece, thereby ruling out the initial choice, is called the Holst theme and it is shown twice here.

Problem 89 is a marvellous demonstration of a triple-underpromotion by White. The black king is in a fortress-like position, which cannot be breached even if White gains a queen on f8. A potential stalemate also looms, when the three mobile black pawns have exhausted their moves. However, White is able to exploit this impending immobility of Black’s force by setting up a zugzwang position. This involves underpromoting on f8 and using the new piece to create a battery on the long diagonal or the first rank. The key 1.Bh8! contains no threat but waits for Black to move the three pawns, each of which causes a different weakness. 1…d6 unguards e6 and allows 2.f8=S h5 3.Se6 g3 4.Sd4, relieving stalemate and forcing 4…Rxb3 5.Sxb3 or 4…Rxc2 5.Sxc2. 1…g3 unguards f3, permitting 2.f8=R d6 3.Rf3 h5 4.Rc3, then 4…Rxb3 5.Rxb3 or 4…Rxc2 5.Rxc2. Lastly, 1…h5 vacates the h6-square and enables 2.f8=B g3 3.Bh6 d6 4.Bc1 Bxc2 5.Bcxb2. This bishop promotion would not have worked against the other initial pawn moves, e.g. 1…d6 2.f8=B? g3! 3.Bxh6 stalemates. Also, the key-bishop must pick the corner square; otherwise it would have interfered with a promoted piece in one of the main variations.