Battery Play

A battery is an arrangement of two pieces capable of giving a discovered attack. The two pieces stand in line with their target, usually the opposing king; when the front piece moves off the line so that the long-range piece from behind attacks the king, the battery is said to be opened or “fired”. The battery is an often-seen device and it sometimes appears as an incidental feature of a problem. Here we look at six compositions where the main thematic play does revolve around the deployment of batteries.

In Problem 43, White’s rook + bishop battery on the d-file cannot fire yet because of the black queen, while the rook + knight battery on the 8th rank cannot open because the knight is required to guard c7. A good key 1.Qb6! gives the black king a flight on d7, and by attacking c7 threatens 2.Sf6. The black queen has various defences to this threat, and four of them permit the rook + bishop battery to operate. 1…Qh5 2.Be2, 1…Qh4 2.Be4, 1…Qh3 2.Bf5, and 1…Qxg5+ 2.Bg6 – in each case the firing bishop shuts off the black queen, i.e. closes a line the piece controls. 1…Kd7 is answered by the double-check 2.Bf5, and the self-blocking 1…Qd7 enables a third white battery to be activated, 2.Se6. One last defence, 1…e6, is met by 2.Qd6.

Problem 44 makes use of set play that involves prominent black checks, 1…Qb5+ 2.Sdc6, 1…Qh3+ 2.Se6, and 1…Qxd4+ 2.Q or Bxd4. (The latter variation, in which White has equally playable alternatives, represents a dual. This is a flaw, especially if the dual occurs in a main variation, though in this instance the fault isn’t serious because it happens only in the set play.) The first two set variations exemplify cross-checks, where White responds to a check by interposing a piece, and simultaneously delivers check or mate. All of these set mates are changed by the key, 1.Qf8! (threat: 2.Qc8), which forms another battery. Now three new cross-checks follow: 1…Qb5+ 2.Sec6, 1…Qh3+ Sef5, and 1…Qxd4+ 2.Sd5. Other black queen defences allow White to exploit the unpin of the knight: 1…Qxe4 2.Sb3, and 1…Qg3 2.Se6.

A half-battery set-up is shown in 45. Here two pieces stand between the line-piece and the enemy king, so that moving either of the intermediate pieces off the line would produce a different battery with the remaining piece. Most half-battery problems contain tries, the solver having to work out which of the two front pieces to move first and where to place it. This example demonstrates excellent changes between try play and actual play. 1.Bf2? has a threat, 2.Bxg3, which is thwarted when Black captures the g5-rook (needed to guard g4). But when either black piece captures on g5, it becomes pinned and enables White to give a battery mate, upon neutralising the other black piece: 1…Rxg5 2.Sd2 and 1…Bxg5 2.Sxc5. If 1…gxf2, then 2.Qxf2, but 1…Rc3! refutes the try. The key 1.Sf2! threatens 2.Rg4, and the same self-pinning defences on g5 lead to a different pair of battery mates: 1…Rxg5 2.Be3 and 1…Bxg5 2.Bxc5. Another changed mate is 1…gxf2 2.Bxf2.

The helpmate 46 incorporates a form of try play – a near-solution of thematic interest. The black king seems likely to be mated on the more restricted c6 square, and after 1.Bb5 and 2.Kc6, Sxd8 would mate. However, any first move by White will disturb the scheme (e.g. 1…Kc8? self-pins the knight), so this is only a try. The actual play sees a new battery created on the long diagonal, changing the front piece from a knight to a rook: 1.Bxb7 Rxb7 2.Kc6 Rb6. In part (b) of this twin, with the black king starting on e6, there is an analogous try and solution: 1.Rde7 White plays?? 2.Kd7 Sxc5, 1.Rxb7+ Bxb7 2.Kd7 Bc8.

The batteries seen in the previous examples are all of the direct type – they aim straight at the king. An indirect battery aims at the king’s adjacent squares. In Problem 47, attempts by White to open both indirect batteries to control the king’s flights just fail to work, e.g. 1.Be3 Bg5 2.Bb6 Re3+ (3.Bxe3), or 1.Rd6 Rf6 2.Rd2 Bd6+ (3.Rxd6). To unpin the mating piece without disrupting the mate, Black is forced to dismantle one of the batteries. 1.Bxf4+ Kg6 2.Bd6 Re3, and 1.Rxe6+ Kg5 2.Re3 Bd6.