Openings From Weimar IV

IN round four I was Black against Ralf Schober (2070), who chose Bird's Opening.

Wikipedia reckons "White's strategic ideas involve control of the e5-square, offering good attacking chances at the expense of slightly weakening" the kingside.

What the article does not mention is the move Bb5(+), which is a common idea in the Bird, especially when Black has played an early ...d5

Often the idea is to exchange the bishop for the black queen's knight, doubling Black's c pawns and increasing White's control of the e5 square.

Our game began 1.f4 c5 2.Nf3 d5 3.e3 g6.

This position occurs 430 times in ChessBase's 2026 Mega database

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Three continuations feature more than 100 times: d4, Be2 and Bb5+.

Capablanca chose our game-continuation, 4.Bb5+, when he reached the position at New York 1931, even though Black has not committed the queen's knight.

The move is also the top choice of Stockfish17.1 and Dragon1, so it clearly has something going for it.

I replied 4...Bd7, and the game continued 5.Qe2 Nc6 6.Bxc6 Bxc6, after which White has increased control of e5, but has given up the bishop-pair without weakening Black's pawn-structure.

Black is slightly better, according to the engines

José Capablanca - Isador Turover, New York 1924, also featured 4...Bd7, but Capablanca answered 5.Bxd7+, which the engines reckon is slightly better than Qe2.

Nevertheless, after the further moves 5...Nxd7 6.Nc3 e6 7.e4 d4 8.Ne2 Ngf6 9.Ng3 h5, Black was slightly better, according to the engines, although White went on to win.

A lot of these moves seem counter-intuitive, at least to me, which may just show gaps in my chess understanding, but I suspect also point to the ideas-richness of chess.