Causes of friction still remained, but they did not develop into open quarrels, for Mitre was content to leave Urquiza in his province of Entre Rios, and the other administrators (caudillos) in their several governments, a large measure of autonomy, trusting that the position and growing commercial importance of Buenos Aires would inevitably tend to make the federal capital the real centre of power of the republic. In 1865 the Argentines were forced into war with Paraguay through the overbearing attitude of the president Francisco Solano Lopez.
In 1864 the ambitious dictator of Paraguay, Francisco Solano Lopez, without previous declaration of war, captured a Brazilian vessel in the Paraguay, and rapidly followed up this outrage by an armed invasion of the provinces of Matto Grosso and Rio Grande in Brazil, and that of Corrientes in the Argentine Republic. A triple alliance of the invaded states with Uruguay ensued, and the tide of war was soon turned from being an offensive one on the part of Paraguay to a defensive struggle within that republic against the superior number of the allies.
The first Christian missions in Paraguay were established by the Franciscans - Armenta, Lebron, Solano (who was afterwards canonized as the " Apostle of Paraguay ") and Bolanos - between 1542 and 1560; but neither they nor the first Jesuit missionaries, Salonio, Field and Ortega, were allowed to make their enterprise a permanent success.
The larger bays on this coast are Tumaco, Choco, Magdalena, Cabita, Coqui, Puerto Utria, Solano, Cupica and Octavia - some of them affording exceptionally safe and well-sheltered harbours.
On the other hand, the eastern part of this zone is the part of Spain which is liable to be visited from time to time by the scorching leveche, the name given in Spain to the sirocco, as well as by the solano, a moist and less noxious east wind.