In all the positions so far a knight has been one move away from striking at two pieces. We now turn to cases where that is not yet so. Whereas the previous positions typically relied on pattern recognition—you see the structural pattern for a fork in place and look for ways to perfect it—the positions here involve the other side of tactical play as well: examining forcing moves to see where they lead. Most often we will begin the train of thought by examining checks and their consequences. Checks are the most forcing of all moves because the choice of replies to them is so limited: your opponent has to reply by capturing the piece threatening his king, or by moving his king, or by interposing something between his king and your threatening piece. And often one or two of those options will be unavailable, reducing more the number of replies you need to worry about.
In the studies that follow, and often in this book, we will alternate between approaches to finding tactical shots. Sometimes we will start by looking for visual clues that suggest a combination may be nearby, and then experiment with ways to perfect it. Sometimes we will start by looking at forcing moves (checks and captures) and see if any patterns come into view as a result of them. It is worth working in both directions because examining the board typically involves a mix of those two approaches.
When you think of examining checks, emphasize the word examine. The point is not to give any check you can, of course; that is a famously bad habit. The point is to consider, before moving, what the results of any check would be, because pushing your opponent’s king around with checks is often a good way to generate tactical opportunities. As you develop tactical skill you will find that always examining every check you can give is overkill and not an efficient use of your limited time; you can afford to quickly dismiss some of them. But at first the danger of overlooking a check and an idea based on it is greater than the risk that you will spend too long looking at such things, so you are better off erring on the side of examining too many checks rather than too few.
To restate these general points in the particular setting of this section: a check may move the king into position to be forked (or be used to create a pin, or a skewer, or a discovery—as we shall see later). That is an especially excellent result, because we already know that kings are ideal targets for double attacks; when your opponent is in check he rarely will be able to use his next move to launch a counterattack. So anytime you deliver a check that forces the king to move, consider whether it has been brought within fresh striking range of a knight or other piece.
Let's turn to examples. In the position to the left White has no fork—yet. There are two ways to find the solution. You might look for a near-fork and see that if Black’s king were pushed onto g7, White would have Ne8+. Or you might start from the other end by examining every available check: asking piece by piece whether you have any way to attack the king and what would happen if you did—what move would be made in response and what the board would look like afterwards. Here White has just one: Ra8. It requires Black to move his king to g7. Now imagine the resulting position and ask what could be done with it—by use of a color scan or by looking for your next check. Either way, see that 2. Ne8+ forks and wins the queen.