Full Moon on the Fifteenth

"Full Moon on the Fifteenth" is a Xiangqi (Chinese Chess) puzzle from the collection Xinwu Endgame Collection. Red moves first and wins in 13 moves; the key first move is +C=4. Below you will find the full solution, what each move achieves, where it could go wrong, and the alternative defences.

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Pieces on the board

Red has a General, a Elephant, 2 Chariots, 2 Cannons, 2 Soldiers. Black has a General, 2 Chariots, a Cannon, 3 Soldiers.

Solution move by move

1. Red +C=4 (check, sacrifices the Cannon, threatens mate next move, the General has no escape square)
Why it works
Creates an immediate mating threat that must be answered.
Takes away the General's escape squares.
What to watch out for
Gives up the Cannon; the follow-up must be exact or the sacrifice is wasted.
Not forcing: the defender has 7 replies, so compare each one before playing it.
1. Black R6+1 (captures the Cannon, threatens mate next move)
1. Black R6+1
2. Red C2=4 (check, threatens mate next move, the General has no escape square)
Why it works
Creates an immediate mating threat that must be answered.
Takes away the General's escape squares.
What to watch out for
Not forcing: the defender has 9 replies, so compare each one before playing it.
The Cannon stands where it can be captured.
2. Black R6=8
2. Black R6=8
3. Red -R=4
Why it works–
What to watch out for
Not forcing: the defender has 32 replies, so compare each one before playing it.
3. Black R3=5 (captures the Soldier, threatens mate next move)
3. Black R3=5
4. Red C4-4 (captures the Soldier, check, the General has no escape square)
Why it works
Wins material: takes the Soldier.
Takes away the General's escape squares.
What to watch out forNo real drawback in this position.
4. Black R5=6 (check)
4. Black R5=6
5. Red K5=4
Why it works–
What to watch out for
Not forcing: the defender has 33 replies, so compare each one before playing it.
5. Black R8+2 (captures the Chariot, threatens mate next move)
5. Black R8+2
6. Red C4+7 (captures the Chariot)
Why it works
Wins material: takes the Chariot.
What to watch out for
Not forcing: the defender has 33 replies, so compare each one before playing it.
6. Black R8+4 (check)
6. Black R8+4
7. Red E5-3 (sacrifices the Elephant, threatens mate next move)
Why it works
Creates an immediate mating threat that must be answered.
What to watch out for
Gives up the Elephant; the follow-up must be exact or the sacrifice is wasted.
Not forcing: the defender has 30 replies, so compare each one before playing it.
7. Black R8=7 (captures the Elephant, check, threatens mate next move, the only legal reply)
7. Black R8=7
8. Red K4+1 (threatens mate next move)
Why it works
Creates an immediate mating threat that must be answered.
What to watch out for
Not forcing: the defender has 36 replies, so compare each one before playing it.
8. Black C5+1
8. Black C5+1
9. Red P7+1
Why it works–
What to watch out for
Not forcing: the defender has 34 replies, so compare each one before playing it.
9. Black R7-8
9. Black R7-8
10. Red P7=6
Why it works–
What to watch out for
Not forcing: the defender has 28 replies, so compare each one before playing it.
10. Black P4=5 (check)
10. Black P4=5
11. Red K4=5 (captures the Soldier)
Why it works
Wins material: takes the Soldier.
What to watch out for
Not forcing: the defender has 23 replies, so compare each one before playing it.
11. Black R7=6 (captures the Cannon)
11. Black R7=6
12. Red R4+5 (captures the Chariot, check, sacrifices the Chariot, threatens mate next move)
Why it works
Wins material: takes the Chariot.
Creates an immediate mating threat that must be answered.
What to watch out forNo real drawback in this position.
12. Black K6+1 (captures the Chariot)
12. Black K6+1
13. Red P6=5 (captures the Cannon, check)
Why it works
Wins material: takes the Cannon.
What to watch out forNo real drawback in this position.
13. Black K6+1
13. Black K6+1

Variations and alternative defences

What if Black defends differently? The alternatives below were checked with the rules engine; lines marked with a mating move lose at once, the others are worth trying on the analysis board.

1. Black R6+1
- If Black plays R6=7 instead: Red mates immediately with C2=4. Try it on the board
- If Black plays R6=8 instead: Red mates immediately with C2=4. Try it on the board
- If Black plays R6=9 instead: Red mates immediately with C2=4. Try it on the board
- If Black plays R6=5 instead: Red mates immediately with C2=4. Try it on the board
- If Black plays R6=4 instead: Red mates immediately with C2=4. Try it on the board
- If Black plays R6=3 instead: Red mates immediately with C2=4. Try it on the board
2. Black R6=8
- If Black plays R6=7 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R6=9 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R6=5 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R6=4 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R6=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R6=2 instead: no immediate mate; the attack continues. Try it on the board
3. Black R3=5
- If Black plays P4+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=5 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P6+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P6=7 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P6=5 instead: no immediate mate; the attack continues. Try it on the board
4. Black R5=6
- If Black plays R8=6 instead: no immediate mate; the attack continues. Try it on the board
5. Black R8+2
- If Black plays P4+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=5 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=1 instead: no immediate mate; the attack continues. Try it on the board
6. Black R8+4
- If Black plays P4+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=5 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=1 instead: no immediate mate; the attack continues. Try it on the board
7. Black R8=7
- If Black plays R8=9 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R8-1 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R8-2 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R8-3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R8-4 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R8-5 instead: no immediate mate; the attack continues. Try it on the board
8. Black C5+1
- If Black plays R7=8 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R7=9 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R7=6 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=5 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R7=4 instead: Red mates immediately with C4=3. Try it on the board
- If Black plays R7=3 instead: Red mates immediately with C4=3. Try it on the board
9. Black R7-8
- If Black plays R7=8 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=9 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=6 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=5 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=4 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays R7=3 instead: no immediate mate; the attack continues. Try it on the board
10. Black P4=5
- If Black plays P4+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P4=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays C5-1 instead: no immediate mate; the attack continues. Try it on the board
11. Black R7=6
- If Black plays P2+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=3 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays P2=1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays C5-1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays C5+1 instead: no immediate mate; the attack continues. Try it on the board
- If Black plays C5+2 instead: no immediate mate; the attack continues. Try it on the board
12. Black K6+1
- If Black plays K6=5 instead: no immediate mate; the attack continues. Try it on the board
13. Black K6+1
- If Black plays K6-1 instead: no immediate mate; the attack continues. Try it on the board

Final position

The record ends here.

Questions about this puzzle

Who moves first in "Full Moon on the Fifteenth"?

Red moves first, as in every puzzle of Xinwu Endgame Collection.

How many moves does the solution take?

13 moves. The main line is shown above; alternative defences are covered in the variations section.

What is the key move?

The first move +C=4 starts the combination. Everything that follows depends on it.

Can I play this position myself?

Yes. Open it on ChessZing, where the board checks your moves and shows the solution if you get stuck.

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