In mid-December 1863 while at the mouth of the Rio Grande River, Captain John Gillis of the USS Ossipee requested instructions on whether he should seize ships bearing legal documentation which were headed for Matamoras, Mexico, if he believed that they bore goods which would later be shipped into Confederate Texas.
Several days later Union Commodore H.H. Bell unequivocally responded, suggesting “the proper course of action …will be to warn off from our waters all legal traders trading with Mexico, and to seize them if they should neglect the warning. Although the [U.S.] Government does not desire to give unnecessary annoyance to neutrals, it expects the officers entrusted with the blockade to do everything within their power to break up... the contraband trade which is known to be carried on there.”