The army remained in camp near Corpus Christi several months. The information Taylor obtained here and reported to Washington indicated no threatening movement on the part of the Mexicans; but on October 4th he suggested that, if the United States government meant to insist on the Rio Grande as the boundary, it would gain an advantage by occupying points on that river. He therefore suggested an advance to Point Isabel and Laredo.[110] Meanwhile had come the attempt to renew diplomatic relations between the United States and Mexico, which ended in failure. January 13, 1846, when it was known in Washington that Slidell would probably not be received by the Mexican government, Taylor was ordered to advance to the Rio Grande.[111] Up to the time of this movement the Mexican government had neglected the distinction in the validity of its claims to the territory east of the Rio Grande. It strenuously asserted the right of Mexico to the whole of Texas, whatever its limits might be, and declared that annexation would be tantamount to a declaration of war. From the Mexican point of view, Taylor invaded Mexico the moment he entered Texas. But when he advanced to the Rio Grande the distinction was finally made. April 12, 1846, he was warned by Ampudia, general in command of the Mexican forces at Matamoras, to retire in twenty-four hours--not beyond the Sabine, as one might have expected from the previous attitude of the Mexican government, but beyond the Nueces.[112] A few days later occurred the first conflict. April 24th a party of dragoons sent out by Taylor was ambushed on the east side of the river by a large force of Mexicans, and after a skirmish, in which a number of men were killed and wounded, was captured.[113] The official report of this affair reached Washington the evening of Saturday, May 9th.[114] President Polk had already decided, in conformity with the judgment of all his cabinet except Bancroft, to send to Congress a message recommending a declaration of war. Now, in formulating the reasons for the declaration, he asserted that “Mexico has passed the boundary of the United States, has invaded our territory, and shed American blood upon the American soil,”[115] and with the unanimous concurrence of his cabinet he sent the message to Congress, Monday, May 11th. On the same day a bill providing for the enlistment of fifty thousand soldiers and the appropriation of ten million dollars, the preamble to which re-echoed the President’s assertion that war existed by the act of Mexico itself, passed the House by a vote of 174 to 14.[116] II CONQUERING A PEACE (1846–1848)