On 9 July 1816, the Congress of Tucumán formalized the Declaration of Independence, which is now celebrated as Independence Day, a national holiday. One year later General Martín Miguel de Güemes stopped royalists on the north, and General José de San Martín took an army across the Andes and secured the independence of Chile; then he led the fight to the Spanish stronghold of Lima and proclaimed the independence of Peru. In 1819 Buenos Aires enacted a centralist constitution that was soon abrogated by federalists.