The next year San Martin, with an efficient army of four thousand men, moved to help the Chilians, and gained a glorious victory over the Spaniards at Chacabuco, not far from Santiago. A year later he won a no less decisive triumph at Maipu (April 5, 1818), which secured the independence of Chile, and by his victories he also strengthened the position of Puirredon and the Government at Buenos Aires. It was now time for constructive work. A Congress assembled once more at Buenos Aires, and, on May 25, 1819, promulgated a federal Constitution on the pattern of the United States of North America. At the same time Puirredon was glad to resign his difficult position, and, in his stead, General Rondeau became Dictator, or President. He was incapable, and the system of government by Juntas or Dictators, which had distracted the country for ten years, came to an end, and seemed likely to be succeeded by even worse conditions, for all the "United Provinces" flew back to particularism and anarchy. But in 1821 the able and honest Rivadavia intervened, and reduced affairs to some semblance of order. In that year also San Martin entered Lima in triumph, and it was clearly necessary to organise the new and sovereign States of South America. In 1822 Lord Londonderry declared for the part of the English Government that "so large a portion of the world could not long continue without some recognised and established relations, and that the State, which neither by its councils nor by its arms could effectually assert its own rights over its dependencies so as to enforce obedience, and thus make itself responsible for maintaining their relations with other Powers, must sooner or later be prepared to see those relations established by the overruling necessity of the case in some other form." The United States had recognised the independence of Argentina, and in 1823 the complicated state of world politics made decisive action necessary. Spain was once more in the grip of France, and it was the object of England to counteract her influence. Accordingly it was intimated to France that England considered the separation of the colonies from Spain as complete, and in the December of that year the United States put forward the celebrated Munroe Doctrine to serve as a warning to France or any other European Power that might cherish transatlantic designs.