◇ Just read — no move neededThe bolt through the door
In the iron bolt (铁门栓), a center cannon pins Black's middle advisor through his own centre pawn — the advisor dare not move, or the cannon fires at the king. Meanwhile Red's general steps onto the rib, and the chariot slams into the advisor's home square f9: taking it is illegal (the generals would face), and the pinned advisor cannot eat the chariot either. d9 is covered by the old soldier on c9.