In a crowded position the problem is rarely that you cannot find a good move — it is that the good move is physically impossible, because your own pieces are in the way. That is when you need clearance.

1. What it is

Clearance means deliberately moving one piece so that it does something useful in a new place, and so that the line it was blocking opens for another piece.

The difference from a discovered attack is one of emphasis:

  • a discovered attack is about the line that opens behind the moving piece;
  • clearance is about the piece arriving somewhere better — opening the line is the bonus.

2. What usually needs clearing

  • Soldiers — pushing a soldier to free a horse is the most common clearance in the opening;
  • Horses — jump the blocking horse away to open a chariot's file;
  • Cannons — move a cannon to free a central cannon, or reposition it onto a better line;
  • Chariots — occasionally a chariot moves to uncover a cannon.

3. Two kinds of clearance

  1. Pure clearance — the main purpose is to open a line; what the moving piece does afterwards hardly matters;
  2. Double-purpose clearance — the piece opens the line and lands somewhere valuable. This is the ideal.

In practice, always look for the double-purpose version first.

4. Is it worth it?

Three questions:

  1. What did you open? Did it really free an important piece?
  2. Where did the piece go? Is it actually doing anything there?
  3. Did you lose tempo? If the move only achieved one of the two, is it still better than what your opponent will do?

If all three answers are good, the clearance works.

5. Why it matters

Clearance is the core tool for unblocking a middlegame. Many positions that look impossible are simply cases of your own pieces standing in each other's way — one sensible clearance and the attack appears.

How to practise:

  1. In your replays, mark which moves were genuine clearance and which were wasted moves;
  2. Set up crowded positions in the endgame editor and practise opening the lines in as few moves as possible.

Read next: the discovered attack and pin guides.