Mr. Seward to Mr. Dickinson
Sir: Information has been received at this department of the formation of an express company in the city of New York, styled the “Mexican Express Company,” for the purpose of aiding the so-called imperial government of Mexico.
You will adopt prompt measures to prevent a violation, in this connexion, by citizens of the United States, or by other persons residing therein, whether by virtue of any charter which that company may have, or may pretend to have, in any way infringing the laws or treaties of the United States, or the law of nations, affecting injuriously the republic of Mexico.
You will diligently watch the operations of this Mexican Express Company, and act in the premises as your sound judgment and discretion shall dictate, with the view of preventing any violation of the just obligations of this government towards the constitutional and recognized government of Mexico.
I have the honor to be, sir, your obedient servant,
Daniel S. Dickinson, Esq., U.S. District Attorney, Southern District of New York, N.Y.