Figure[White to move]

More Complicated Cases.

Now let's try some cases where there is more than one complication to address. Here we will start to see some problems where none of the ingredients of a fork is obviously in place at the beginning. This makes spotting the potential for a double attack harder. Instead of looking for obvious tip-offs like loose pieces the queen can attack or available checks, we have to use a little more imagination; we look for familiar visual patterns and we examine checks, captures, and threats, searching for signs that a fork is coming into view.

In the position pictured here, ask whether Black has any loose pieces; you thus are led to the knight at e4. White can’t attack it and give check at the same time; indeed, White has no checks at all. But if White’s queen moved to a4 it would be close to executing the classic pattern seen at the beginning of the chapter, attacking the king and a loose piece on the fourth or fifth rank: the queen at least would be aimed at both pieces, with its path to the king blocked by the knight at c6 and its path to the loose knight at e4 blocked by its own pawn at d4. So White looks for ways to get rid of those blockages, preferably at the same time. He starts by moving the obstruction he can control (his own d4 pawn), and using it to threaten the obstruction controlled by the enemy. Thus d4-d5 attacks the knight and forces it to move out of the way. Now Qa4+ wins the knight at e4.