Wagenbach Defense

The Wagenbach Defense, 3...h5, prepares ...h4 followed by ...g5, a chain that would hold the f4-pawn without allowing the undermining h2-h4 that troubles Black in the Classical lines. The cost is time, and White usually develops with 4. Bc4 or strikes in the center with 4. d4; engines give White a clear advantage. Named after the English club player János Wagenbach, it appears mainly as a surprise in casual and fast games.