Starting position #856
Back-rank setup: RBKNBRNQ
SP-856 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
Move the pieces right on the board — full Chess960 rules, castle by dropping the king on the rook.
Position features
The king starts on c1, the rooks on a1 and f1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionGuard family; read right to left it becomes position 109.
The engine's main line opens with e4, putting a pawn straight into the centre.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 78 Morozov Balance Index: 78 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +18 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 209 of 960 by balance — 1 is the most balanced start.
- Balance band S — slight edge · dynamics along the play-out: volatile
- Evaluation along the engine's main line (60 half-moves): +13 → -25 → -21 → -12
Position facts
- Mirror twin: position #109
- The king starts on c, the rooks on a and f
- It becomes the daily position in 128 days
Puzzles from this position
- Attack on the uncastled king: pawn to b6 (a5·2) — Chess960 specifics · 780
- Winning blow: rook to f3 (f1·2) — Chess960 specifics · 920
- Winning blow: bishop to e6 (a2·3) — Chess960 specifics · 1200
- Winning blow: knight to d5 (c3·11) — Chess960 specifics · 1200
- Winning blow: rook to c7 (c3·3) — Chess960 specifics · 1290
- Mate in 3: bishop to d6 (c5) — Chess960 specifics · 1630
- Winning blow: queen to d8 (c7·4) — Chess960 specifics · 1870
- Chess960 tactic on d5 (h1) — Chess960 specifics · 2120
- Mate in 3: knight to d5 (b4) — Chess960 specifics · 2170
- Attack on the uncastled king: rook to e8 (e7·2) — Chess960 specifics · 2400
This position appears in course day 70
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Commentary
The king already stands on c1 and the rook already occupies f1, so each castling sends a single piece — the rook one way, the king the other. The queen begins in the corner on h1, the second rook in the other corner on a1. The bishops are on b1 and e1, one on each colour. Every pawn on the second rank begins with a defender — this setup concedes nothing on move one. The knights are on d1 and g1, and White's edge is a narrow +18 centipawns: e4 f5 exf5 Nh6 f4 a5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.