Probably more than nine tenths of the material used in the preparation of this work is in fact new. No previous writer on the subject had been through the diplomatic and military archives of either belligerent nation, for example. Virtually a still larger percentage is new, for the published documents needed to be compared with the originals. In the printed American reports relating to the battles of September 8 and 13, 1847, for instance, over fifty departures from the manuscripts, that seemed worth noting, were found. Nor did the additional documents prove by any means to supply mere details. A great number of unprinted statements from subordinate officers, who were nearer to the facts than their superiors could be, were discovered. The major official reports needed both to be supplemented and to be corrected. Such reports were in most instances colored more or less, and in some radically distorted, for personal reasons or from a justifiable desire to produce an effect on the subordinates concerned, the army in general, the writer's government, the enemy, and the public at home and abroad; while, as General Scott stated in orders, unintentional omissions and mistakes were "common." Taylor's account of the battle of May 9, 1846, for example, failed completely to explain his victory. It has been only by obtaining and comparing a large number of statements that approximate verity has been reached. The same has been true of the diplomatic and political aspects of the subject. The reports of the British, French and Spanish ministers residing at Mexico, to cite one illustration, proved indispensable. In reality, therefore, aside from its broader outlines the field presented ample opportunities for study; and while no doubt so extended an investigation included many facts of slight value, La Rochefoucauld was right when he said, "To know things perfectly, one should know them in detail."[P.3] As a particular consequence of this full inquiry, an episode that has been regarded both in the United States and abroad as discreditable to us, appears now to wear quite a different complexion. Such a result, it may be presumed, will gratify patriotic Americans, but the author must candidly admit that he began with no purpose or even thought of reaching it. His view of the war at the outset of his special inquiries coincided substantially with that prevailing in New England, and the subject was taken up simply because he felt convinced that it had not been studied thoroughly. This conviction, indeed, has seemed to be gaining ground rapidly for some time, and hence it is believed that new opinions, resting upon facts, will be acceptable now in place of opinions resting largely upon traditional prejudices and misinformation.