Starting position #851
Back-rank setup: BRKNRNQB
SP-851 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
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 b1 and e1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 99.
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 80 Morozov Balance Index: 80 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +17 centipawns for White (depth 42, 400 000 000 nodes).
- Rank 183 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): +42 → 0 → 0
Position facts
- Mirror twin: position #99
- The king starts on c, the rooks on b and e
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 43 days
Puzzles from this position
- Attack on the uncastled king: queen to h7 (d3) — Chess960 specifics · 780
- Winning blow: knight to g6 (e7·2) — Chess960 specifics · 920
- Winning blow: pawn to f6 (e5·8) — Chess960 specifics · 1060
- Winning blow: queen to b7 (h1·2) — Chess960 specifics · 1110
- Attack on the uncastled king: rook to e8 (e1·18) — Chess960 specifics · 1200
- Winning blow: rook to f8 (c8·4) — Chess960 specifics · 1280
- Attack on the uncastled king: queen to b7 (h1·17) — Chess960 specifics · 1320
- Winning blow: king to e2 (d1·23) — Chess960 specifics · 1390
- Attack on the uncastled king: queen to a8 (h1·14) — Chess960 specifics · 1630
- Chess960 tactic on d6 (f5·3) — Chess960 specifics · 2350
This position appears in course day 115
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Commentary
Both bishops start in the corners, on a1 and h1, each with a single long diagonal — one to h8, the other to a8. The king already stands on c1, so long castling moves the rook alone; the rooks are on b1 and e1. Among the pawns, a2 begins without a defender, and the pawn on c2 leans on the king alone. The queen is on g1, the knights on d1 and f1 — both can reach e3, so a knight move there has to name its file. White's edge is a narrow +17 centipawns, and after b3 opens the long diagonal the published line ends with Black's bishop capturing on a1: e4 g5 g3 b6 b3 Bxa1.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.