137. Black blocks its own general, by the soldier

Helpmates in xiangqi

4 moves

Black moves first and both sides cooperate: Black, Red, Black, Red, and Red's second move mates. Black has 32 legal first moves and exactly one of them works. 21 pieces, Black 38 to Red 14 in material, mate by the soldier. Themes: Black blocks its own general, a quiet first move…