President Buchanan had appointed experienced diplomat Robert Milligan McLane of Maryland as minister plenipotentiary to Mexico a month earlier with the charge to ascertain if the government of Benito Juarez, then embroiled in the War of Reform, was worthy of recognition. On April 7, 1859, McLane presented his credentials to Juarez at Vera Cruz thereby conferring United States recognition. This was significant for Juarez since recognition remained in force through the French-supported imperial government of Maximilian I that ruled Mexico between 1863 and 1867. (By John Osborne)
John Bassett Moore, Francis Wharton, A Digest of International Law: As Embodied in Diplomatic Discussions, Treaties and Other International Agreements .... Volume I (Washington DC: Government Printing Office, 1906), 147.