Figure[Black to move]

In this one the idea, at least, should be visible from the start; as long as you are careful to look for alignments between White pieces, you can't fail to see his king and queen on the same rank. A skewer comes to mind—but how? Black cannot yet maneuver his queen—his only plausible piece for the purpose—into position behind White's king. Yet with well-placed checks miracles sometimes are possible, and here the needed miracle would be minor: some combination of pushing White’s king toward his queen and getting Black’s queen on the other side of them both.

The only checks Black can give are with his queen, but there are several: Qe1, Qf1, and Qg1; Qb2, Qc2, and Qd2; Qe3; and Qf4. These don't all require much analysis, of course. Several of them lose the queen right away, and others, such as the checks on the first rank, drive White’s king up the board where it has lots of room to run and Black is likely to lose control over it. Most promising, then, is Qf4+: safe for the queen, and since it pressures the king from above it keeps the escape options for it narrow—especially in conjunction with the bishop on d3. White’s only reply is Ke1 (if he plays Kg1, Black mates with Qf1). The mission is partly accomplished: Black’s queen has gotten behind White’s king. Now the alignment of White’s king and queen must be restored. Black uses the safe check Qf1+, where the queen has protection from its bishop. This forces the king off the first rank and back onto the second one: Kd2. The skewer has been prepared. Next for Black comes Qxg2+; the best White can do is play KxB and allow his queen to be taken. (Notice that instead of Qxg2+ Black can play Qe2+ to try to protect his bishop. But then White moves his king to c3 and will take the bishop anyway after Black plays QxQ.)

If you are more than a check away from arranging a skewer—if, as here, you need to push the enemy king around more extensively to get everything into place—your queen often will have to play an important role. Its flexibility of movement allows it to inflict successive checks from different angles that are very useful. But usually you also will need another piece as well to play the sorts of roles the bishop did here, such as cutting off some of the king’s flight squares and providing cover for the queen as it gives snug checks. There are more examples of both themes to come.