"The attack on Castro was the next object. He was at Santa Clara, an intrenched post on the upper or south side of the Bay of San Francisco, with 400 men and two pieces of field artillery. A circuit of more than a hundred miles must be traversed to reach him. On the 6th of July the pursuit was commenced, by a body of 160 mounted riflemen, commanded by Colonel Fremont in person, who, in three days, arrived at the American settlements on the Rio de los Americanos. Here he learnt that Castro had abandoned Santa Clara, and was retreating south toward Ciudad de los Angeles (the city of the Angels), the seat of the Governor General of the Californias, and distant 400 miles. It was instantly resolved on to pursue him to that place. At the moment of departure, the gratifying intelligence was received that war with Mexico had commenced; that Monterey had been taken by our naval force, and the flag of the United States there raised on the 7th of July; and that the fleet would coöperate in the pursuit of Castro and his forces. The flag of independence was hauled down, and that of the United States hoisted, amidst the hearty greetings and to the great joy of the American settlers and the forces under the command of Colonel Fremont. "The combined pursuit was rapidly continued; and on the 12th of August, Commodore Stockton and Colonel Fremont, with a detachment of marines from the squadron and some riflemen, entered the City of the Angels, without resistance or objection; the Governor General, Pico, the Commandant General, Castro, and all the Mexican authorities, having fled and dispersed. Commodore Stockton took possession of the whole country as a conquest of the United States, and appointed Colonel Fremont Governor, under the law of nations; to assume the functions of that office when he should return to the squadron. "Thus, in the short space of sixty days from the first decisive movement, this conquest was achieved by a small body of men, to an extent beyond their own expectation; for the Mexican authorities proclaimed it a conquest, not merely of the northern part, but of the whole province of the Californias. "The Commandant General, Castro, on the 9th of August, from his camp at the Mesa, and next day 'on the road to Sonora,' announced this result to the people, together with the actual flight and dispersion of the former authorities; and at the same time, he officially communicated the fact of the conquest to the French, English, and Spanish Consuls in California; and to crown the whole, the official paper of the Mexican government, on the 16th of October, in laying these official communications before the public, introduced them with the emphatic declaration, 'The loss of the Californias is consummated.'