On the 7th of June, 1846, while at Mazatlan, Commodore Sloat received satisfactory information that the Mexican troops had crossed the Rio Grande and had attacked the army of General Taylor in Texas. At the same time he learned that our squadron in the Gulf had put some of the Mexican ports under blockade. Of course he had not yet heard of the declaration of war passed on the 12th of May; but he knew that according to the policy of the administration this meant war, and that under his instructions he was to begin offensive operations. Leaving the "Warren" at Mazatlan, he sailed at once in the "Savannah" for Monterey. The commodore showed great foresight in striking his first blow in California. The country was mostly unexplored, and only sparsely inhabited, many of the settlers having come from the United States. Its resources were not fully known, but they were supposed to be considerable, though nothing was looked for like the Eldorado that was afterward discovered. It embraced an immense territory, comprising, besides the State of California as its boundaries are fixed to-day, Nevada, Utah, New Mexico, Arizona, and part of Colorado. Its position pointed it out as the part of Mexico which could most advantageously be transferred in case of an annexation of territory at the end of the war. Annexation would be made much easier by an early conquest, and indeed a conquest was in some degree necessary to make the ground of cession. It was a vulnerable point, because it was garrisoned only by a small force of Mexican troops, and it lay too far from the scene of active hostilities to be recovered from the Americans if they once got full possession. The "Savannah" arrived at Monterey on the 2d of July, and found there the "Cyane" and the "Levant." Commodore Sloat hastened to demand a surrender from the Mexicans, and upon their refusal, two hundred and fifty seamen and marines were landed, who took possession of the town without resistance. Soon after a proclamation was published declaring that California had become a part of the United States. A company of volunteer dragoons was organized among the Americans on shore, and preparations were made to seize the neighboring towns. While this was going on at Monterey, Commander Montgomery in the "Portsmouth," which was at Yerba Buena, or San Francisco, as it is now called, having received an order from the commodore, took like measures to assert the authority of the United States. He also organized his military companies, and assumed control of all the posts in the neighborhood,--Sonoma, Sutter's Fort, and the Presidio. Not far off, in the interior, Frémont, a young captain of topographical engineers, who was at work upon his duties of surveying, had raised the American flag, and at various points he too had taken a nominal possession. On the 19th of July he joined Commodore Sloat at Monterey.