London, July 21, 1860.

Sir: My mission to the International Congress terminated abruptly, even before the first regular meeting for the transaction of business.

At the appointed time (16th instant) a preliminary meeting was called, to appoint officers and arrange the order of business for the regular meetings. All the foreign delegates were declared to be vice-presidents, and, by invitation of the chairman, took their seats as such upon the stand. Lord Brougham was, I think, the last member of the Congress who entered the hall, and was applauded from the first glimpse of him until he took his seat; it was near and to the left of the chair. Mr. Dallas, appearing as a complimentary visitor,[4] was seated to the right, in a rather conspicuous position. Things thus arranged, the assembly waited the presence of his royal highness, the prince consort, who was to preside and open the meeting with an address. He soon appeared, delivered his address, and took his seat. As soon as he concluded, and the long-continued plaudits ceased, Lord Brougham rose, complimented the speech very highly and deservedly, and requested all who approved of it to hold up their hands. We did so, of course. This done, he turned to Mr. Dallas, and addressing him across the prince’s table, said, “I call the attention of Mr. Dallas to the fact that there is a negro present (or among the delegates), and I hope he will have no scruples on that account.” This appeal was received by the delegates with general and enthusiastic applause. Silence being restored, the negro, who goes by the name of Delany, rose and said, “I thank your royal highness and Lord Brougham, and have only to say that I am a man.” This, too, was applauded warmly by the delegates. I regarded this an ill-timed assault upon our country, a wanton indignity offered to our minister, and a pointed insult offered to me. I immediately withdrew from the body. The propriety of my course is respectfully submitted to my government.

What England can promise herself from exciting the ire of the United States, I cannot divine. Surely there is nothing in the past history of the two countries which offers to her the least encouragement to seek contests with the great republic, either national or individual. Will not her championship of the slave against his master be in full time when the slave shall complain of his lot and solicit her interference.

My reasons, more at large, for the course that I have pursued, will be found in the London Morning Chronicle, herewith transmitted, which, in its slightly-modified form, I pray you to regard as a part of my report.

I am, sir, your most obedient, humble servant,

A. B. Longstreet.

Hon. Howell Cobb, Secretary of the Treasury.

The American Delegate and Lord Brougham.

To the Editor of the Morning Chronicle.