The mobilization was effected with great promptness, and on the 15th of March, through the Secretary of War and the Secretary of the Navy, in a letter addressed to the Chief of Staff, I issued the following instructions: It seems my duty as Commander in Chief to place troops in sufficient number where, if Congress shall direct that they enter Mexico to save American lives and property, an effective movement may be promptly made. Meantime, the movement of the troops to Texas and elsewhere near the boundary, accompanied with sincere assurances of the utmost goodwill toward the present Mexican Government and with larger and more frequent patrols along the border to prevent insurrectionary expeditions from American soil, will hold up the hands of the existing Government and will have a healthy moral effect to prevent attacks upon Americans and their property in any subsequent general internecine strife. Again, the sudden mobilization of a division of troops has been a great test of our Army and full of useful instruction, while the maneuvers that are thus made possible can occupy the troops and their officers to great advantage. The assumption by the press that I contemplate intervention on Mexican soil to protect American lives or property is of course gratuitous, because I seriously doubt whether I have such authority under any circumstances, and if I had I would not exercise it without express congressional approval. Indeed, as you know, I have already declined, without Mexican consent, to order a troop of Cavalry to protect the breakwater we are constructing just across the border in Mexico at the mouth of the Colorado River to save the Imperial Valley, although the insurrectos had scattered the Mexican troops and were taking our horses and supplies and frightening our workmen away. My determined purpose, however, is to be in a position so that when danger to American lives and property in Mexico threatens and the existing Government is rendered helpless by the insurrection, I can promptly execute congressional orders to protect them, with effect. Meantime, I send you this letter, through the Secretary, to call your attention to some things in connection with the presence of the division in the Southwest which have doubtless occurred to you, but which I wish to emphasize.