In 1810, he joined the nationalist rebels fighting for independence from Spain. In 1814, his Chilean rebels were defeated by the Spanish and retreated into the Andes. In 1817, O'Higgins went back on the offensive with the aid of Argentine General José de San Martín. On February 12, 1817, he led a cavalry charge that won the Battle of Chacabuco. He became the first leader of independent Chile, and was granted dictatorial powers as Supreme Director on February 16, 1817. On February 12, 1818, Chile was proclaimed an independent republic.