Starting position #428
Back-rank setup: RBNQNKBR
SP-428 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
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 d1.
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 b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
One second-rank pawn starts with no defender at all: b2.
The setup belongs to the BastionGuard family; read right to left it becomes position 732.
The engine's main line opens with f3.
Every sentence here is computed from the setup itself and can be checked on the board.
Balance
MBI 86 Morozov Balance Index: 86 of 100 — class A — most balanced.
- Engine evaluation of the starting position: +15 centipawns for White (depth 50, 400 000 000 nodes).
- Rank 135 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 (70 half-moves): +21 → +16 → +16 → 0
- Deeper check (1 200 000 000 nodes, depth 53): +10 cp, -5 cp against the base run — verified · E — even
Position facts
- Mirror twin: position #732
- The king starts on f, the rooks on a and h
- It becomes the daily position in 364 days
Puzzles from this position
- Attack on the uncastled king: knight to e6 (c5·2) — Chess960 specifics · 780
- Attack on the uncastled king: rook to h2 (h1·3) — Chess960 specifics · 780
- Attack on the uncastled king: pawn to a3 (b2·22) — Chess960 specifics · 780
- Attack on the uncastled king: rook to a5 (a1·3) — Chess960 specifics · 780
- Attack on the uncastled king: knight to d7 (e5·16) — Chess960 specifics · 1090
- Winning blow: bishop to h6 (e3·2) — Chess960 specifics · 1110
- Winning blow: knight to f6 (h5·13) — Chess960 specifics · 1290
- Mate in 2: bishop to d4 (f2) — Chess960 specifics · 1630
- Winning blow: queen to d8 (f6·2) — Chess960 specifics · 1870
- Chess960 tactic on f6 (d8) — Chess960 specifics · 2400
This position appears in course day 35
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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 are on b1 and g1, the queen on d1. Among the pawns, b2 is the one that begins without a defender. The knights are on c1 and e1. The search ran to depth 50 here and calls it +15 centipawns: f3 f6 c3 c6 Bf2 e5.
Written from the measured facts above and checked against the board before publishing. All 960 positions have one.