The condition of the Brazilian forces was very different.  In the first place, little heed had been taken to make ready for anything of the kind, and another factor which proved greatly to the disadvantage of the fighting material involved lay in the difficulty of communication between Rio de Janeiro and those portions of the great Empire which bordered on Paraguay.  Thus Lopez’s invading army, when it swept through the Brazilian province of Matto Grosso, met with practically no resistance worthy of the name, and, in the absence of defending troops, it might, undoubtedly, have taken possession of vast tracts of country, and have continued to hold these indefinitely.

It was Lopez’s bizarre and wild ambition which frustrated his own schemes.  A single tide of invasion was not sufficient to satisfy a mind such as his.  Gathering together a second powerful army, he determined to strike at the south-eastern portion of Brazil in addition to its province of Matto Grosso.  In order to effect this he demanded in arrogant tones from Argentina permission for his troops to cross the Argentine province of Corrientes.  To this, as neutrals, it was impossible for the Argentines to consent.  As a result, Lopez in a fury declared war upon Argentina, and, as though even this did not suffice, he next found himself at grips with the Uruguayan forces.

Thus Brazil, Argentina, and Uruguay were now leagued together against the armies of the despot Lopez.  With a view of alienating the sympathies of the oppressed subjects of the Dictator from their tyrannical leader, the allies caused it to be widely proclaimed that the war they were waging was not directed against the Paraguayan people in general.  It was against Lopez alone that they were fighting, they asserted.  The claim was true enough, since this was in reality the position of affairs.  Nevertheless, owing to the methods of Lopez, the proclamation carried far less weight than had been anticipated.

The Paraguayan forces now penetrated into the Argentine province of Corrientes, seized the capital, Corrientes itself, and took possession of a couple of steamers—­the Gualeguay and the 25 de Mayo—­which were anchored in the river opposite to that town.  The Paraguayan fleet now held command of the river system up-stream of Corrientes.  On June 11, 1865, the allied naval forces, steaming up the Parana, came into contact with the hostile fleet.  A battle was fought, which ended in the defeat of the Paraguayan squadron, which was forced to retreat, crippled and damaged, to the north.

A succession of actions now took place on land, and the Paraguayans, although fighting with a desperate heroism, were gradually beaten back and driven across their own frontiers.  At the same time, the army which had invaded Brazil retired in sympathy, and the scene of the war changed to Paraguay itself, which was in its turn invaded by the forces of the triple alliance.  One of the most sanguinary battles of the war was fought on May 24, 1866—­very nearly a year after the first naval action off the river port of Corrientes.