In June, 1845, General Taylor had been directed to select and occupy, on or near the Rio Grande del Norte, such a site as would be best adapted to repel invasion and to protect our Western border. But on the 8th of July following, the Secretary of War (Mr. Marcy) addressed the following letter to him. "This Department is informed that Mexico has some military establishments on the East side of the Rio Grande, which are, and for some time have been, in the actual occupancy of her troops. In carrying out the instructions heretofore received, you will be careful to avoid any acts of aggression, unless an actual state of war should exist. The Mexican forces at the posts in their possession, and which have been so, will not be disturbed as long as the relations of peace between the United States and Mexico continue." On the 30th July, 1845, the Secretary again addresses Gen. Taylor as follows: "You are expected to occupy, protect and defend the territory of Texas, to the extent that it has been occupied by the people of Texas. The Rio Grande is claimed to be the boundary between the two countries, and up to this boundary you are to extend your protection, only _excepting_ any posts on the Eastern side thereof, which are in the actual occupancy of Mexican forces, or _Mexican settlements_, over which the Republic of Texas did not exercise jurisdiction at the period of annexation, or shortly before that event. It is expected, in selecting the establishment for your troops, you will approach as near the boundary line, the Rio Grande, as prudence will dictate. With this view, the President desires that your position, for a part of your forces at least, should be west of the River Nueces."