Gentlemen: Yesterday, at 3 a. m., the long-contemplated move to force the passage of Humaita was made, when an unheard-of cannonade commenced, which was truly awful; the heavy artillery of the iron-clads and monitors was fired in rapid succession, while the guns of the fortress were quickly plied. This continued till 10 a. m. without a moment’s pause; the reports came faster than one could count; those of the enemy made the loudest sound, as the mouths of their guns were pointed in the direction of the Chaco, while those of the Brazilians were directed in an opposite way. Both parties made a lavish use of shells, explosive shot, and Congreve rockets. A dense cloud of white smoke covered the horizon as the firing was going on. As for the results of the infernal din, all that can he said with certainty is, that three iron-clads and three monitors have passed the obstruction, and are above Humaita, where they are annoying the enemy from the north, while those that remain below are not inactive. On board of the gunboats there is a grand display of bunting, music, and much glee. Nothing is known positively of the affair other than the iron-clads and monitors were maltreated somewhat in the passage, and the fortress badly mauled. It could not be otherwise, as the cannonade was kept up at close quarters.

It is now 12 m.; firing of heavy artillery has been going on at intervals since early dawn. It is the prevalent belief that Humaita will soon surrender. It is out of the question to forward any details at the present moment that may be relied upon. All is wild excitement and bustle. The weather is awfully hot, particularly so for the past few days.

Truly yours,