Arenales retreated to the frontier of Santa Cruz, taking his arms and spare ammunition with him on mule-back. Reinforced by Warnes he halted at Abapo on the Rio Grande, and in March had two hundred and four infantry and four small guns. Warnes refused to recognise his authority, and took up a position for himself at Horcas with a thousand men, advancing his outposts to Herradura and Petacas, passes of the Cordillera considered impregnable, as they were nothing more than flights of stairs cut in the sides of the mountain.
At the same time the Indians of the Chaco along the banks of the river Pilcomayo rose up in favour of the Patriots; guerilla chiefs aroused a part of the Province of La Plata; and the towns in Blanco’s rear were again in insurrection. Pezuela despatched Colonel Benavente with five hundred men, against this new insurrection; but in spite of sundry advantages gained by both columns, Benavente was so weakened that he was soon reduced to inaction, and Blanco, whose troops suffered greatly from fever, was forced to evacuate the Valle Grande early in April and to retreat to Misque.
Arenales, while encamped at Tumina, received information that Blanco, resuming the offensive, had forced the passes of Herradura and Petacas, and had dispersed the division under Warnes. He at once marched towards the scene of action, and met Warnes at the head of only three hundred men. The latter, learning wisdom by his reverses, placed himself under his orders. Blanco had in the meantime taken the city of Santa Cruz, and was now coming in search of them with six hundred men, of whom one-half were regular infantry.
On the 24th May the Royalists came in sight, and the Patriots retreated by a narrow defile, leaving a small party to draw on the enemy. At dawn on the 25th they reached the town of La Florida, on the river Piray. Arenales took up a position on the right of this small river, in an open space where the bank was about two yards high. Below, the river spread out, while in front lay a wide plain. His flanks were protected by dense brushwood; the town was behind him. He planted his guns on the open, placed his cavalry in ambuscade on each flank, with Warnes in command on the right and De la Riva on the left. At the foot of the bank he opened a trench, concealed by sand and brushwood, where he stationed his infantry, kneeling, and awaited the attack. His entire force numbered about eight hundred men.
Just before noon the same day a dropping fire was heard in the woods in front. It came from the outpost, who were retreating before the enemy. Soon after that the Royalist column debouched from the wood, preceded by skirmishers. Blanco drew up his men on the plain, with strong cavalry reserves on the flanks, and opened fire with his four-pounders. Then, as the infantry advanced firing, the Patriot guns opened upon them. When the skirmishers entered the river, the entrenched infantry poured in a volley, and, springing from their shelter, charged through the smoke with such impetuosity that, aided by the cavalry on the left, they completely routed the enemy, Colonel Blanco remaining dead upon the field.
Arenales headed the pursuit in person with so little caution that he was attacked by a group of fugitives, who left him for dead with fourteen wounds, three of them in the face. His men rushed in and saved him, carrying him on their shoulders back to the camp.
Two flags, two guns, two hundred muskets, one hundred killed, and ninety-nine prisoners, were the trophies of this victory, while the Patriots lost only one man killed and twenty-one wounded, including their leader.
Such was the action of La Florida, which saved Santa Cruz de la Sierra and compelled the retreat of the Royalist army from Salta. It gives the name to one of the principal streets of Buenos Ayres. For it Arenales was raised to the rank of general, and a badge of honour was decreed to the troops engaged.
Arenales was no sooner well of his wounds than he marched with his division and reoccupied the Valle Grande, routing a Royalist force of two hundred men at Postrer Valle on the 4th July, but was on the 5th August himself defeated at Sumapaita. Afterwards reinforced by Padilla with a body of Indian slingers, he forced Benavente to retreat from Tomina, and again reoccupied the Valle Grande.
Eighteen months he maintained this extraordinary war at a cost to the enemy of 1,300 men in killed, wounded, and missing, entering Cochabamba at last in triumph, and joining the Argentine army with 1,200 men.