William Walker’s later expeditions to Nicaragua justifiably don’t get the same attention that his successful conquest of the country does. He lost, after all. But one brought him to the attention of the United States Congress.
On December 8, 1857, Commodore Hiram Paulding, in command of the United States Navy’s Home Squadron, arrested Walker and hauled him back to New York. Commodore Paulding seized Walker for violating the Neutrality Act. Paulding did not take it on himself to go after Walker. Rather he had orders to do just that. In the ensuing debates over the capture, on January 21, 1858, the Congressional Globe quotes this letter, dated September 14, 1857:
The undersigned, Minister Plenipotentiary of the Republic of Guatemala and Salvador, and the Chargé d’Affaires of the Republic of Costa Rica, have the honor to make known to the Secretary of State of the United States, that there is no doubt that there is being prepared, in the southern part of this Republic, an expedition under the orders of the adventurer William Walker, the which, according to the advices published in the public journals, will sail about the middle of the present month, or the beginning of the next, and will proceed to Bocas del Toro, where it will receive the armament which has been prepared in this port of New York to be forwarded to said point. It is probable that the uniting of the expeditionists and the aforesaid armament, at Bocas del Toro, may be for the purpose of these new invaders of Nicaragua entering the port of San Juan del Norte, for they have no other port at which they can enter. The undersigned hope that the Government of the United States, in view that it cannot prevent the debarkation of this expedition, so publicly and shamelessly announced, like all the others, will order that a vessel of war of the United States Prevent the landing of these aggressors in the Bocas del Toro, and that positive orders be given to the vessel of war that may be lying in San Juan del Norte, also to prevent the landing of the said filibusters on that coast, causing them to return to the United States, as transgressors of the laws of this country, and as disturbers of the peace and security of friendly nations.
Four days later, Secretary of State Lewis Cass of popular sovereignty fame, put out a circular letter to the various naval commands:
From the information received at this Department, there is reason to believe that lawless persons are now engaged within the limits of the United States in setting on foot and preparing the means for military expeditions to be used against the territories of Mexico, Nicaragua, and Costa Rica–Republics with whom the United States are at peace–in direct violation of the sixth section of the act of Congress, approved 20th April, 1818. And, under the eighth section of said act, it is made lawful for the President, or such person as he shall empower, to employ the land and naval forces of the United States, and the militia thereof, “for the purpose of preventing the carrying on of any such expedition of enterprise from the territories or jurisdiction of the United States.” I am, therefore, directed by the President to call your attention to the subject, and to urge you to use all due diligence, and to avail yourself of all legitimate means at your command, to enforce these and other provisions of the said act of 20th April, 1818, against those who may be found to be engaged in setting on foot or preparing military expeditions against the territories of Mexico, Costa Rica, and Nicaragua, so manifestly prejudicial to the national character, and so injurious to the national interest. And you are hereby instructed to promptly communicate to this Department the earliest information you may receive relative to such expeditions.
When asked by another officer in a similar situation, Secretary of the Navy Isaac Toucey offered more detailed instructions:
American citizens have a right to travel and go where they please, when engaged in lawful pursuits, but not to violate the laws of their own or any country. They have the right to expatriate themselves and to become citizens of any country which is willing to receive them, but not to make that right a mere cloak and cover for a warlike expedition against it or its Government. Your instructions do not authorize you to act arbitrarily or upon mere suspicion. You will not seize an American vessel, or bring her into port, or use the force under your command to prevent her landing her passengers, upon mere suspicion. You will be careful not to interfere with lawful commerce. But where you find that an American vessel is manifestly engaged in carrying on an expedition or enterprise from the territories or jurisdiction of the United States against the territories of Mexico, Nicaragua, or Costa Rica, contrary to the sixth section of the act of Congress of April 20, 1818, already referred to, you will use the force under your command to prevent it, and will not permit the men or arms engaged in it, or destined for it, to be landed in any port of Mexico or Central America.
Paulding had orders to arrest Walker and did so with the blessing of both United States and Central American authorities. He had a clear basis in American law to do so. Walker’s own activities gave evidence beyond mere suspicion, as noted by the Central American diplomats in warning the State Department. But those facts settled nothing and the arrest provoked a major controversy, arising at length in Congress on January 7, 21, 28, and then again in April 8, 1858.