Starting position #538
Back-rank setup: RNKQBBNR
SP-538 · 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 h1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The pawn on b2 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 517.
The engine's main line opens with d4, 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 61 Morozov Balance Index: 61 of 100 — class B — balanced.
- Engine evaluation of the starting position: +23 centipawns for White (depth 49, 400 000 000 nodes).
- Rank 370 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): +28 → +21 → 0
Position facts
- Mirror twin: position #517
- The king starts on c, the rooks on a and h
- It becomes the daily position in 154 days
Puzzles from this position
- Attack on the uncastled king: queen to b4 — Chess960 specifics · 780
- Attack on the uncastled king: pawn to a3 (b2·13) — Chess960 specifics · 780
- Winning blow: pawn to f4 (g3·8) — Chess960 specifics · 920
- Winning blow: queen to c5 (d5) — Chess960 specifics · 1060
- Winning blow: knight to b5 (c3·16) — Chess960 specifics · 1200
- Winning blow: queen to c5 (d5·2) — Chess960 specifics · 1280
- Winning blow: king to b1 (c1·34) — Chess960 specifics · 1390
- Mate in 3: bishop to f5 (d3·2) — Chess960 specifics · 1630
- Attack on the uncastled king: queen to a6 (e2·7) — Chess960 specifics · 1990
- Chess960 tactic on d6 (f4) — Chess960 specifics · 2350
This position appears in course day 46
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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 e1 and f1, the knights on b1 and g1. Among the pawns, b2 leans on the king alone; no other second-rank pawn starts short of a defender. The queen is on d1 beside her king, the second rook in the corner on h1. The engine takes the centre with d4 and the line runs d4 d5 Nf3 e6 c4 dxc4.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.