When the Black Horse is on file 4, rank 9 and the Red Horse is on file 5, rank 6 in a crossed-leg formation, the Red Chariot on file 2, rank 9 and the Red Cannon on file 7, rank 5 create a dangerous 'empty cannon' situation. The board shakes as the Black General on file 5, rank 8 must weigh between defense and counterattack.