Figure 6.2.2.4[White to move]

Once you have diagonal pressure through g7 to h8, your task is to open the h-fileā€”in other words, to get rid of the enemy pawn that obstructs it. We've seen that one way to eliminate the pawn is to capture it. Another is to require it to capture, usually by taking something it protects. Here is an example of how the latter approach can be used to achieve our current mate. In this case the standard sequence we already saw would work fine: sacrifice the rook on h7; move the queen to the h-file; mate on h8. But even more efficient is 1. Qxg6+, h7xQ; 2. Rh8#. This only works when the pawn on f7 is pinned (as it is here) and unable to recapture on g6, or when that pawn is gone and f7 is blocked off to the king by another enemy piece or by pressure from one of yours. The broad point of the example, in any event, is just that there may be more than one way to open a file.