Starting position #51
Back-rank setup: BNNRQKRB
SP-51 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
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 d1 and g1, the queen on e1.
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 a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: c2, h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 899.
The engine's main line opens with g3.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 59 Morozov Balance Index: 59 of 100 — class B — balanced.
- Engine evaluation of the starting position: +24 centipawns for White (depth 49, 400 000 000 nodes).
- Rank 409 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 (56 half-moves): +28 → +8 → 0
Position facts
- Mirror twin: position #899
- The king starts on f, the rooks on d and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 186 days
Puzzles from this position
- Attack on the uncastled king: queen to d8 (h4) — Chess960 specifics · 620
- Winning blow: rook to d5 (d1·2) — Chess960 specifics · 780
- Attack on the uncastled king: rook to h1 (g1) — Chess960 specifics · 780
- Attack on the uncastled king: knight to a4 (c3·22) — Chess960 specifics · 780
- Winning blow: knight to e7 (d5·10) — Chess960 specifics · 920
- Attack on the uncastled king: queen to c7 (c2) — Chess960 specifics · 1150
- Winning blow: king to g2 (f1·15) — Chess960 specifics · 1250
- Mate in 2: knight to e7 (f5·3) — Chess960 specifics · 1320
- Attack on the uncastled king: knight to e6 (f4·11) — Chess960 specifics · 1650
- Chess960 tactic on g5 (f3·2) — Chess960 specifics · 2400
This position appears in course day 6
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Commentary
Short castling swaps the king on f1 with the rook on g1; long castling moves the king alone, since the rook already occupies d1. Both corners hold a bishop — a1 towards h8, h1 towards a8 — each with a single diagonal and a single pawn to unlock it. The queen stands on e1 next to the king, the knights on b1 and c1. The pawns on c2 and h2 begin with no defender at all. The line in the dataset opens g3 g6, then c4 c5 Nb3 d6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.