Starting position #558
Back-rank setup: RNKNQBBR
SP-558 · BastionGuard — King off-centre on c or f with both knights on inner files.
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 h1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 500.
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 75 Morozov Balance Index: 75 of 100 — class B — balanced.
- Engine evaluation of the starting position: +19 centipawns for White (depth 46, 400 000 000 nodes).
- Rank 235 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): +25 → +31 → +17 → 0
Position facts
- Mirror twin: position #500
- The king starts on c, the rooks on a and h
- It becomes the daily position in 1370 days
Puzzles from this position
- Attack on the uncastled king: pawn to b3 (c2·3) — Chess960 specifics · 780
- Attack on the uncastled king: bishop to b5 (f1·4) — Chess960 specifics · 780
- Winning blow: bishop to e8 (g6) — Chess960 specifics · 920
- Winning blow: rook to f6 (f1·2) — Chess960 specifics · 1010
- Attack on the uncastled king: bishop to e6 (c4·4) — Chess960 specifics · 1420
- Mate in 2: queen to b8 (f8) — Chess960 specifics · 1450
- Mate in 3: queen to b6 (d6) — Chess960 specifics · 1630
- Winning blow: rook to h7 (f7·3) — Chess960 specifics · 1870
- Winning blow: knight to c7 (e6·3) — Chess960 specifics · 2060
- Chess960 tactic on c8 (b8·2) — Chess960 specifics · 2120
This position appears in course day 68
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Commentary
The king already stands on c1, so long castling moves the rook alone from a1. The bishops sit together on f1 and g1, the knights on b1 and d1. The pawn on c2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on e1, the second rook in the corner on h1. The engine takes the centre with e4 and Black answers in kind: e4 e5 f3 f6 Ne3 Nbc6.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.