The passions of these guerrillas had been violently inflamed by the persuasions and advice administered by a shrewd Mexican priest, named Gabriel Gonzales, who, fearing probably a loss of clerical influence among the native population, and inheriting, with all his race, a natural antipathy to the march of the Anglo-Saxon, consequent upon the secession of the territory, made unceasing efforts by every means in his power to have a strong blow struck for its salvation. He partially succeeded.

The original scheme of the Mexican leaders was, in the first instance, to have made a concentrated attack upon the town of La Paz, at the time in possession of a company of the New York regiment, under Lt. Colonel Burton; but perceiving the weakness of the force to contend against, in the small garrison of San José, and deeming it an easy prey, they divided their force, and with the moiety resolved upon its destruction.

Hardly had the squadron disappeared below the horizon from San José, before reports came flying thick and fast, that a serious attack was contemplated. These rumors only infused renewed energy in the preparations for defence and resistance, nor was the garrison kept long in suspense.

On the morning of the 19th, ten days after the sailing of the ships of war, a small cavalcade, bearing a banner of truce, entered the village, and by a blast of trumpets demanded a parley. Possibly, to give additional weight to the summons, clouds of dust were beheld rolling down the valley, and strong squadrons of cavalry scouring the roads and underwood, in advance of their main body. The effect was not realized. The flag of truce was met by an equal number from the Cuartel, and a missive received, demanding, under the high appeal of Dios Patria y Libertad, an immediate surrender, under penalty of the horrors of annihilation by a greatly superior force. The reply was prompt and decisive: the American commander regretting his inability to comply with the summons, and declaring his intention to defend his flag against all odds.

Negotiations being thus courteously terminated, the guerrillas, nearly two hundred strong, skirted the suburbs, and took up a position on the right of the American quarters, behind the church, on an elevation, three hundred and fifty yards distant, laterally commanding the town; it was called La Lomita.

During the afternoon the Mexican eagle and tricolor was unfurled, and with cheers and pealing bugles, they opened a fire from a six-pounder and musketry, continuing the work until dark. The shot, however, did but little damage to the soft adobie walls, save fracturing cornices or boring fresh apertures for loop holes; nor was it judged prudent to return their salutes but rarely, inasmuch as the carronade of the Cuartel could not, without much difficulty, be brought to bear upon the enemies' hill, and the limited supply of ammunition rendered it advisable to await closer quarters with the small arms.

As night closed around the valley, there was a cessation of firing; the garrison remaining under arms momentarily anticipating a more vigorous attack; nor were they disappointed. By ten o'clock the besiegers had cautiously crept within close proximity to the occupied buildings, and with a field piece in the main street, began a simultaneous assault from all directions, front and rear. Showers of bullets flew into every hole and aperture of the Cuartel, whilst determined efforts were made to gain a lodgment in the opposite house: but they were severally repulsed with loss, and not an ounce of lead was thrown away, or powder idly burned without a definite object. Three of the garrison only, were wounded.

A hot but ineffective fire was kept up by the assailants during the night, but at daylight the force was withdrawn again to the camp at La Lomita. All the following day the garrison were encircled by the guerrillas, who maintained a brisk fire of musketry from behind the walls and parapets of adjoining dwellings. The disparity of numbers was too great to risk the chances of dislodging them at the point of the bayonet.

With the night the garrison were still under arms at their posts The plan of the guerrillas was to have stormed the front of the Cuartel with forty picked men, under cover of three field pieces, receive the discharge from the nine-pounder, rush in, and capture it, whilst other bodies, provided with bars and ladders, were to scale the azoteas, and then pour in a destructive fire on the occupants below. In the end, these matured calculations were defeated: nevertheless, the positions were well chosen, and the Mexicans in readiness for the assault. Just before midnight the garrison sentinels challenged: the hail was immediately answered by trumpets sounding a charge, and a heavy fire from guns and small arms; at the same instant, Mejares, the commandant of artillery, with four of his followers, in leading the forlorn hope, were riddled by rifle balls from the besieged, whilst another in striving to bear away the body of his comrade, fell mortally wounded on the same bloody heap. Deprived of the animating example of their leader, the storming parties faltered, thus disconcerting the entire movement, and they returned to their encampment without attempting further demonstrations that night. Eight newly made graves was the sole glory reaped in this abortive struggle.

Meanwhile a series of vigorous attacks had already been commenced upon the command at La Paz, but was repulsed by a stouter resistance than was anticipated; equally unprepared for the gallant conduct of the little band at San José, and depressed by the loss of their leader, the guerrilla chiefs ordered their partisans to again unite in the north, for a combined movement upon La Paz—as had been originally intended.