The creation of the Peru–Bolivian Confederation by Marshal Andrés de Santa Cruz caused great alarm in the neighboring countries. The potential power of this confederation aroused the opposition of Argentina and, above all, Chile, due not only to its great territorial expanse but also to the perceived threat that such a rich state signified for the area. Diego Portales, arguably the most important Chilean statesman of the 19th century, who at the time was the power behind president José Joaquín Prieto, was very concerned that the new Confederation would break the regional balance of power and even be a threat to Chilean independence, and so immediately became its enemy.