In the latter part of August, Herrera, with a few Americans, was sent to one of the cattle-estates of Los Llaños, and while carelessly driving cattle toward Tipitapa he was attacked and slain by a small band of Legitimists. This incident occurred not many miles from Tipitapa, and in consequence of it Lieut.-Col. McDonald received orders to cross the Tipitapa river, and marching toward Los Llaños, to ascertain whether any traces of the enemy were to be seen in that direction. The roads were, at the time, difficult, and all movements were necessarily slow and uncertain, owing to the heavy rains of the season. McDonald, however, with Capt. Jarvis, and about forty men, proceeded in the direction of San Jacinto, a large cattle-estate a few miles east and north of Tipitapa. It was reported that some of the enemy were quartered at the country-house belonging to the estate, and McDonald, arriving near the house before daybreak, postponed a nearer approach until he might be able to see the strength of the enemy. Soon after daylight he drew up his force for an attack, but while proceeding at a quick pace he was received by such a sharp, steady fire that he deemed it prudent to withdraw. Capt. Jarvis was brought off mortally wounded, and McDonald had ascertained that the enemy were in larger numbers than he expected, and strongly barricaded behind adobes. The presence of the enemy at San Jacinto was a serious inconvenience to the commissariat, and when it was known at Granada there were numerous volunteers who proposed to drive the Legitimists from the house they occupied. The state of the roads made it almost impossible to send artillery against San Jacinto, even had there been the round shot or shell requisite for rendering a gun useful in an attack on adobes. There was a general impression at Granada that McDonald’s Rifles had retired too soon, and the impression was due to the utter want of discipline in the corps. Seeing the enthusiasm of some officers and citizens, and desirous of ascertaining more exactly the strength of the enemy beyond Tipitapa, Walker consented that volunteers should be engaged for an attack on San Jacinto.