Starting position #403
Back-rank setup: BRQNNKRB
SP-403 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
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 b1 and g1, the queen on c1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 739.
The engine's main line opens with g3.
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 166 of 960 by balance — 1 is the most balanced start.
- Balance band S — slight edge · dynamics along the play-out: equalizing
- Evaluation along the engine's main line (60 half-moves): +12 → +27 → +25 → +2
Position facts
- Mirror twin: position #739
- The king starts on f, the rooks on b and g
- King and rook are neighbours — castling from adjacent squares feels unusual
- It becomes the daily position in 215 days
Puzzles from this position
- Attack on the uncastled king: bishop to e5 (a1) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to f4 (g3·36) — Chess960 specifics · 780
- Attack on the uncastled king: king to h2 (g2·2) — Chess960 specifics · 780
- Winning blow: knight to f4 (g6) — Chess960 specifics · 1110
- Winning blow: knight to c5 (d3·13) — Chess960 specifics · 1200
- Attack on the uncastled king: queen to c5 (e3·3) — Chess960 specifics · 1290
- Winning blow: knight to f5 (e3·22) — Chess960 specifics · 1480
- Winning blow: knight to d6 (c4·11) — Chess960 specifics · 1560
- Winning blow: queen to e5 (d5·5) — Chess960 specifics · 1700
- Chess960 tactic on f7 (f3) — Chess960 specifics · 2400
This position appears in course day 30
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Commentary
Both corners hold a bishop, a1 towards h8 and h1 towards a8, each with a single diagonal. In the engine's line the first one is traded off in place: after g3 g6 b3 comes Bxa1, and White takes back on the corner square: Rxa1 c5. Short castling swaps the king on f1 with the rook on g1. Two pawns begin with no defender at all: a2 and h2, and e2 leans on the king alone. The queen is on c1, the knights on d1 and e1.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.