Four days after the consummation of this project Mr. Webster took his seat in the Senate, and on March 11 wrote to his son that, “while we feel as we ought about the annexation of Texas, we ought to keep in view the true grounds of objection to that measure.  Those grounds are,—­want of constitutional power,—­danger of too great an extent of territory, and opposition to the increase of slavery and slave representation.  It was properly considered, also, as a measure tending to produce war.”  He then goes on to argue that Mexico had no good cause for war; but it is evident that he already dreaded just that result.  When Congress assembled again, in the following December, the first matter to engage their attention was the admission of Texas as a State of the Union.  It was impossible to prevent the passage of the resolution, but Mr. Webster stated his objections to the measure.  His speech was brief and very mild in tone, if compared with the language which he had frequently used in regard to the annexation.  He expressed his opposition to this method of obtaining new territory by resolution instead of treaty, and to acquisition of territory as foreign to the true spirit of the Republic, and as endangering the Constitution and the Union by increasing the already existing inequality of representation, and extending the area of slavery.  He dwelt on the inviolability of slavery in the States, and did not touch upon the evils of the system itself.

By the following spring the policy of Mr. Polk had culminated, intrigue had done its perfect work, hostilities had been brought on with Mexico, and in May Congress was invited to declare a war which the administration had taken care should already exist.  Mr. Webster was absent at this time, and did not vote on the declaration of war; and when he returned he confined himself to discussing the war measures, and to urging the cessation of hostilities, and the renewal of efforts to obtain peace.

The next session—­that of the winter of 1846-47—­was occupied, of course, almost entirely with the affairs of the war.  In these measures Mr. Webster took scarcely any part; but toward the close of the session, when the terms on which the war should be concluded were brought up, he again came forward.  February 1, 1847, Mr. Wilmot of Pennsylvania introduced the famous proviso, which bears his name, as an amendment to the bill appropriating three millions of dollars for extraordinary expenses.  By this proviso slavery was to be excluded from all territory thereafter acquired or annexed by the United States.  A fortnight later Mr. Webster, who was opposed to the acquisition of more territory on any terms, introduced two resolutions in the Senate, declaring that the war ought not to be prosecuted for the acquisition of territory, and that Mexico should be informed that we did not aim at seizing her domain.  A similar resolution was offered by Mr. Berrien of Georgia, and defeated by a party vote.  On this occasion