What was name of film in which one army holds their shields at sun and the reflection of shields causes other army to fall to deaths down a ravine?

The film you are referring to is "300," directed by Zack Snyder and released in 2006. In this stylized retelling of the Battle of Thermopylae, the Spartan soldiers use their shields to reflect sunlight, blinding the Persian forces and causing chaos, which leads to some falling to their deaths down a ravine. The scene exemplifies the film's dramatic visuals and intense battle sequences.