394 Texas annexed. War with Mexico. [i845-6 amendment giving the President the option of submitting to Texas the joint resolution or opening a new negotiation for annexation by treaty. Tyler chose to offer annexation under the joint resolution ; and on March 3, 1845, a messenger was accordingly despatched to Texas. The Texan Congress adopted the resolution in June ; a convention of the people ratified annexation in July; and in December, 1845, Congress formally admitted the State of Texas into the Union. The Mexican government had repeatedly informed the United States that the annexation of Texas would be regarded as a declaration of war. No sooner therefore did the joint resolution pass than the Mexican Minister asked for his passports and left Washington. The Mexican Minister of Foreign Affairs, on hearing of the resolution, dismissed the American Minister; and in March, 1845, all diplomatic relations were severed. In the following June, General Zachary Taylor was ordered to march from New Orleans to the mouth of the Sabine river, a part of the boundary line between Texas and the United States. On July 30, 1845, Taylor was instructed to occupy and defend Texas so far as it was occupied by Texans ; and in August the army of occupation camped at Corpus Christi on the Nueces river, across which the jurisdiction of the Republic of Texas had never extended. An Act of the Texan Congress had indeed (December 19, 1836) declared the Rio Grande from its mouth to its source, and a meridian from its source to degree 42 of north latitude, to be the western boundary of the Republic ; but between the Nueces and the Rio Grande was the Mexican State of Tamaulipas; and above this and bounding Texas on the west and north-west were Coahuila, Chihuahua, and New Mexico. At Corpus Christi Taylor remained till March, 1846, when, in obedience to orders, he crossed the Nueces and stood on Mexican soil. A march of seventeen days brought the army to the east bank of the Rio Grande, where Taylor pitched his camp, built Fort Brown, and trained his guns on the public square of the Mexican town of Matamoras on the western bank of the river. On April 11 General Ampudia entered Matamoras with 2500 men, and notified Taylor to break up his camp within twenty-four hours and retire behind the Nueces. Taylor replied that he was under the orders of his govern- ment ; and that, if Ampudia crossed the Rio Grande, the act would be considered that of an enemy and as such would be resisted. Twenty- seven miles east of the American camp and on the shore of an inlet from the Gulf of Mexico was Point Isabel, where Taylor had established a depot of military supplies for the army of occupation. Hearing that bodies of Mexicans had crossed the river above and below Fort Brown, Taylor at once sent out a squadron of dragoons in each direction to reconnoitre. The squadron sent below the camp reported no enemy in sight, but that which went above was surprised, surrounded, and captured (April 23). In this condition of affairs an officer rode into camp, reported the