In 1837, Echeverría founded the Asociación de Mayo, at the back room of his store. The meeting was first viewed favorably by top functionaries of the Rosas government, even though they were considered suspicious by the Sociedad Popular Restauradora (Rosas' government's political arm). In the same year, the French blockade of the Río de la Plata started, which first for cultural reasons, then political, defined them as anti-Rosas. The threats of the para-military group, the "Mazorca", Sastre did not flee to Montevideo, as several of his friends had done. The government's displeasure and the stopping of imports from France caused the bankruptcy of his bookstore. In 1840, Sastre published a novel, "Cartas a Germania".