The Phalanx hit the Persian Infantry line, but instead of the usual thunder clap of steel hitting steel, there was a harsh, drawn out snapping sound. The line was hit with such force that the Persian's wicker shields, useful in entangling an attacker's spear, burst apart and disintergrated under the press of Greek bronze. Persian archers desperately shot point blank into the advancing hoplites, but could not penetrate their heavy armor. The Greek Phalanx was unstoppable.