Dutch Defense

The Dutch Defense to the Polish Opening arises after 1. b4 f5, a rare reply in which Black transfers the familiar Dutch approach to a flank opening. Instead of opening the f8-bishop's diagonal to attack the loose pawn on b4, as 1...e5 or 1...e6 do, Black claims the e4-square with a wing pawn and keeps the option of building a Stonewall or Leningrad-style setup. The cost is that b4 faces no immediate pressure, so White can develop freely, and the move slightly loosens the black kingside. The engine gives White a slight edge.

White almost always answers 2. Bb2, which accounts for the large majority of games. The bishop takes the long diagonal toward g7 and adds pressure to e5, discouraging Black from supporting the f-pawn with ...e5. Nf3 and e3 are the other moves the engine prefers. The advance 2. b5 and the prophylactic 2. a3 are seldom chosen, and White's results with 2. a3 are noticeably worse. Online results after 1...f5 are close to even, and decisive games greatly outnumber draws.