Starting position #939
Back-rank setup: RKRNBQNB
SP-939 · RampartGuard — King pushed to the b- or g-file, knights off the edges — 144 positions here.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on b1, the rooks on a1 and c1, the queen on f1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartGuard family; read right to left it becomes position 17.
The engine's main line opens with a4.
Every sentence here is computed from the setup itself and can be checked on the board.
Opening: main line
Stockfish's main line from the start of this setup, 15 moves deep (100 million nodes per move):
1. g4 a5 2. a4 g6 3. Ra3 f5 4. gxf5 gxf5 5. f4 Nf6 6. Nf3 d6 7. Nd4 Nd7 8. Bf2 Ra6 9. Qh3 Bg6 10. Nb3 Nb6
Evaluation after the line: 0.00 for White.
Best first moves for White (evaluation in pawns):
- g4 — +0.20
- f4 — +0.16
- a4 — +0.16
Balance
MBI 61 Morozov Balance Index: 61 of 100 — class B — balanced.
- Engine evaluation of the starting position: +23 centipawns for White (depth 48, 400 000 000 nodes).
- Rank 364 of 960 by balance — 1 is the most balanced start.
- Balance band S — slight edge · dynamics along the play-out: stable
- Evaluation along the engine's main line (60 half-moves): +25 → +5 → +9 → 0
Position facts
- Mirror twin: position #17
- The king starts on b, the rooks on a and c
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 330 days
Puzzles from this position
- Winning blow: pawn to c7 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to e6 (e5) — Chess960 specifics · 920
- Winning blow: queen to c7 (f4·3) — Chess960 specifics · 1010
- Mate in 2: bishop to c7 (b8) — Chess960 specifics · 1220
- Winning blow: king to a2 (b2·2) — Chess960 specifics · 1250
- Winning blow: rook to g8 (g6·4) — Chess960 specifics · 1280
- Winning blow: queen to d5 (a5·2) — Chess960 specifics · 1390
- Mate in 2: queen to a6 (a3·2) — Chess960 specifics · 1670
- Winning blow: queen to b5 (d5·4) — Chess960 specifics · 1930
- Chess960 tactic on b7 (b4) — Chess960 specifics · 2250
This position appears in course day 25
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Commentary
The king begins on b1 with a rook on either side of him, on a1 and c1, and short castling takes him five squares across the board to g1. A bishop holds the corner on h1 with one diagonal to a8; the second bishop is on e1. On the second rank, h2 is the one that begins without a defender. The queen is on f1, the knights on d1 and g1. White's edge is a narrow +23 centipawns, and the first four half-moves come in matched pairs: a4 a5 f4 f5 d3 Nf6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.