The Battle of Rancagua, also known as the Disaster of Rancagua occurred in October 1814 when the Spanish under Mariano Osorio defeated rebel Chilean forces.
On October 1, the insurgents started to battle in Rancagua in an attempt to prevent the expeditionaries from taking Santiago, Chile. Brigadier Osorio's second in command, Rafael Maroto, manifesting a disdain for his opponents typical of officials recently arrived in the Americas, ordered his troops to attack the enemy fortifications without bothering to send in either scouts or guerrillas. The result was that the so-called Talaveras regiment, bombarded by the volley of shots, was forced to retreat with heavy losses.
On the next day, Bernardo O'Higgins managed to make his way past the royal troops and retreat to the capital, where his opponents entered without resistance a few days later. This led to the harsh reconquista rule of the Spanish.