Polk meant to invade Mexico, and had made no provision for the intended war.
The President having thus made, on his own responsi- bihty, ample provision for the commencement of the war, in- structed Taylor how he might bring it on in case Mexico remained passive. On the 30th August, he was told, " The assembling a large Mexican army on the borders of Texas, and crossing the Rio Grande with a considerable foi'ce, will be regarded by the Executive as an invasion of the United States {/) and the commencement of hostilities. An at- tempt to cross the river with such a force will also be con- sidered in the sama light. In case of war, either declared or made manifest hy hostile acts, your main object will be the protection of Texas ; but the pursuit of this object will not necessaril}'^ confine your action within the territory of Texas. Mexico having thus commenced hostilities, you may in your discretion cross the Rio Grande, disperse or capture the forces assembled to invade Texas, defeat the junction of troops uniting for that purpose, drive them from their positions on either side of the river, and, if deemed practicable and expedient, take and hold possession of Metamoras and other places in the country."
Thus we find the President in time of peace, and without the knowledge or expectation of Congress, ordering the invasion of a territory in the actual and exclusive possession of Mexico, a territoiy having Mexican villages under the authority of Mexican magistrates, a port of entry, a custom-house, and various " military establishments."
Should the Mexicans, prompted by the natural dictates of patriotism and self-defence, assemble a body of troops which in General Taylor's discretion might be deemed "large," and attempt to cross the river to reinforce their miHtaiy establishments, to protect their villages, to secure the collection of their customs, to watch the motions of'the invading army, then. General Taylor is to regard their conduct as an invasion of