The annexation of Texas, it can justly be said, was a very interesting, important, complicated and critical affair. It involved issues and consequences of no little moment in our domestic politics. It gave us an area greater than England and France together, with a port that ranks very near the head of our list, and paved the way for the acquisition of San Francisco and our far Southwest. It led to our greatest and most brilliant foreign war. It extinguished a nation that might have become a strong and unfriendly rival and might have caused the disruption of the Union. It removed an excellent opportunity for certain leading European powers to interpose in the affairs of this continent and in particular to embarrass the development of the United States. It presented a field of battle on which our diplomats and those of England, France, Mexico and Texas waged a long and intricate struggle with all their skill and with a full determination to succeed; and it brought these five nations to the verge of war. Such an episode would appear to merit a detailed study, especially since very different opinions regarding it still prevail; and as the author, while gathering data for a history of our Mexican War, found many essential materials for a thorough treatment of the subject, he has felt under obligation to complete and present them.<br><br>As the footnotes indicate, the monograph is based almost exclusively (with the exception of certain preliminary matters) on first-hand sources, though all previous works of any importance on the subject have been fully examined. Use has been made of substantially all the diplomatic papers - American, British, French, Mexican and Texan - bearing upon the question, and also, as may be seen by the account of the Sources in the Appendix, a rather large amount of other valuable material both manuscript and printed, such as executive and legislative documents, letters, speeches, diaries and periodicals. All discoverable sources of information, indeed, have been examined. In this way a closer approach to completeness has been attainable, and at the same time it has been possible to avoid errors into which a writer depending upon a portion of the data would not infrequently fall without even suspecting danger.