Starting position #501
Back-rank setup: RQBBNKNR
SP-501 · 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 a1 and h1, the queen on b1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
The pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 554.
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 83 Morozov Balance Index: 83 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +16 centipawns for White (depth 45, 400 000 000 nodes).
- Rank 159 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 (44 half-moves): +34 → 0 → 0
Position facts
- Mirror twin: position #554
- The king starts on f, the rooks on a and h
- It becomes the daily position in 449 days
Puzzles from this position
- Winning blow: queen to f6 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to d5 (e4·27) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to e6 (d5·27) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to e4 (d3·51) — Chess960 specifics · 780
- Attack on the uncastled king: knight to d7 (c5·13) — Chess960 specifics · 920
- Winning blow: rook to d2 (d1·6) — Chess960 specifics · 1060
- Mate in 2: bishop to d4 — Chess960 specifics · 1220
- Winning blow: rook to f7 (f5·2) — Chess960 specifics · 1290
- Winning blow: queen to d7 (d5) — Chess960 specifics · 1560
- Winning blow: pawn to c6 (c5·16) — Chess960 specifics · 2340
This position appears in course day 70
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Commentary
Castling is ordinary in both directions from f1, with the rooks in the corners on a1 and h1. The bishops stand side by side on c1 and d1, one on each colour. On the second rank, f2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on b1, the knights on e1 and g1 — both can reach f3, so the engine's fifth half-move carries a letter: Nef3. The engine takes the centre first: e4 e5 c3 Ne7 Nef3 c5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.