The Assembly initially had a higher authority than the triumvirate, but to help in the warfare, it granted it higher power afterwards. In need of an even stronger government, it replaced the triumvirate as executive power with the Supreme Director, a unipersonal office. Congress of Tucumán The Supreme Director of the United Provinces of the Río de la Plata replaced the role of the triumvirate. The first one was Gervasio Antonio de Posadas, the uncle of Carlos María de Alvear, replaced by Alvear himself some time afterwards. Facing an adverse context in the war of independence, Alvear considered turning the United Provinces into a British protectorate, which motivated a coup against him. The Assembly of the Year XIII was closed, but a new one was formed later, the Congress of Tucumán. To avoid the animosity against Buenos Aires, it was not located in that city but in Tucumán. The Congress did not include deputies from the provinces ruled by Artigas, and included others from provinces which are currently part of Bolivia. The Congress finally declared the independence of the United Provinces. There was a plan to move the capital to Cusco and crown an Inca as king, which was resisted by Buenos Aires. The Congress then moved to Buenos Aires, which could influence them better. The Inca plan was forgotten, and the Congress drafted the 1819 constitution. This constitution did not choose a specific type of government, but the elites in Buenos Aires thought to bring a European prince to Buenos Aires and appoint him king. Estanislao López and Francisco Ramírez resisted the project, and attacked Buenos Aires. Neither San Martín nor Belgrano provided military help. Buenos Aires fell in the battle of Cepeda, which ended the authority of the Supreme Directors. The defeat started the , a period where the provinces would rule themselves without a national head of state. Anarchy With the defeat of Buenos Aires in Cepeda, the country was left without a head of state. An open cabildo in Buenos Aires elected a new governor, Manuel de Sarratea, who negotiated the Treaty of Pilar with Ramírez and López. The treaty guaranteed national unity and a federalist system of government, the end of hostilities between the provinces, and called for a new congress to decide a new national government. This congress, however, was never called because of the ongoing wars. The Banda Oriental was invaded by the