James K. Polk of Tennessee was elected, Texas was admitted to the Union, and the Mexican War resulted. War was declared by Congress May 11, 1846, vigorously prosecuted, and Mexico was defeated. By the terms of the treaty, concluded February 2, 1848, New Mexico and Upper California were given to the United States. Webster, who had been returned to the Senate by Massachusetts, opposed the war as he had the annexation of Texas. At this time a double sorrow came to him. His second son, Major Edward Webster, a young man of fine abilities, courage, and high sense of honor, died near the city of Mexico, from disease induced by exposure. His body arrived in Boston May 4, and, only three days before, Webster's lovely daughter, Julia, who had married Samuel Appleton of Boston, was carried to her grave by consumption. Her death, at thirty, was beautiful in its resignation and faith, even though she left five little children to the care of others. Her last words were, "Let me go, for the day breaketh," which words were placed upon her tombstone. Mr. Webster was indeed crushed by this new sorrow. He wrote to his friend Mrs. Ticknor, "I cannot speak of the lost ones; but I submit to the will of God. I feel that I am nothing, less even than the merest dust of the balance; and that the Creator of a million worlds, and the judge of all flesh, must be allowed to dispose of me and mine as to his infinite wisdom shall seem best." In 1848, when Mr. Webster was sixty-six, the presidency once more eluded his grasp by the nomination of another "available" man, General Zachary Taylor, one of the heroes of the Mexican War. Webster had spoken earnestly for Harrison and Clay; now he was unwilling longer to work for the party which had ignored him and nominated a man whom, though an able soldier, he thought unfitted for the place as a statesman. If it was a mistake to show that he was wounded in spirit, as it undoubtedly was for so great a man, it was nevertheless human. The thing which Mr. Webster had feared these many years was now coming to pass. A violent agitation of the slavery question in the Territories was upon the nation. For thirty years slavery had been odious to the North, and carefully nurtured by the South. In 1820, when Missouri was admitted as a State, the North insisted that a clause prohibiting slavery should be inserted as a condition of her admission to the Union. Henry Clay devised the compromise by which slavery was prohibited in all the new territory lying north of latitude 36° 30', which was the southern boundary of Missouri. This line was called Mason and Dixon's line, from the names of the two surveyors who ran the boundary line between Maryland and Pennsylvania.