Starting position #391
Back-rank setup: QRBNNKRB
SP-391 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on f1, the rooks on b1 and g1, the queen on a1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
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 BastionGuard family; read right to left it becomes position 754.
The engine's main line opens with b3.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 69 Morozov Balance Index: 69 of 100 — class B — balanced.
- Engine evaluation of the starting position: +21 centipawns for White (depth 41, 400 000 000 nodes).
- Rank 305 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): +36 → +31 → +15 → 0
Position facts
- Mirror twin: position #754
- The king starts on f, the rooks on b and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 1184 days
Puzzles from this position
- Mate in 1: knight to h6 — Chess960 specifics · 620
- Attack on the uncastled king: bishop to h8 (b2·4) — Chess960 specifics · 780
- Attack on the uncastled king: bishop to h6 (c1·10) — Chess960 specifics · 780
- Attack on the uncastled king: queen to d4 (a1·8) — Chess960 specifics · 780
- Attack on the uncastled king: knight to c7 (d5·18) — Chess960 specifics · 920
- Winning blow: knight to f6 (e4·12) — Chess960 specifics · 1150
- Winning blow: queen to f8 (a3·2) — Chess960 specifics · 1200
- Winning blow: queen to g7 (a1·2) — Chess960 specifics · 1430
- Winning blow: pawn to c8 (d7) — Chess960 specifics · 1870
- Winning blow: knight to f5 (e3·27) — Chess960 specifics · 2400
This position appears in course day 5
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Commentary
Short castling swaps the king on f1 with the rook on g1. A bishop holds the corner on h1 with one diagonal to a8; the second bishop is on c1 and steps to b2 as soon as the b-pawn moves: b3 b5 Bb2 c5 Ne3 Bb7. The queen starts in the far corner on a1. The pawn on h2 has no defender, and e2 leans on the king alone. The knights are on d1 and e1.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.