Knox, the Secretary of War, sent his advice on the same day as the Vice-President. He mentioned the danger to the United States if England should get the Mississippi Valley. The true interests of the country dictated neutrality. Spain, he said, would not enter the war unless supported by France, and such support was not unexpected. If it should be given, France would attempt to associate the United States with her in the war. One of the parties might offer sufficient inducement to the United States to enter the war, or they might be obliged to enter the war on their own account to avert a greater evil.[370]
More than two weeks later Hamilton sent a long discussion of the question from the standpoint of national right and from the standpoint of expediency. He concluded that if Great Britain should ask the privilege, it would be best for the United States to agree to it and then explain the matter to Spain. If troops should be marched across without consent having been asked, it would be a cause of war and would have to be resented or a great national humiliation borne. Hostilities, he thought, should be delayed as long as possible.[371]
While these precautionary measures were being considered by the Government at New York, instructions were being sent to the American diplomatic agents in Europe to guide them in case of a breach between England and Spain. On August 11 Jefferson wrote instructions for Col. David Humphreys, whom he was sending to Europe as a secret agent of the United States. Humphreys was to go first to London, where he should deliver instructions to Morris, the American informal agent at that place. After delivering these he was to proceed by way of Lisbon to Madrid, where he should deliver instructions to Carmichael, the American chargé at the Spanish Court.[372]
Morris had been watching the progress of the dispute between England and Spain and had been in close touch and sympathy with French representatives.[373] The letter which Humphreys carried instructed Morris to intimate to the British Court in case of war that the United States could not be indifferent to the prospect of England’s acquiring territory in the adjoining Spanish possessions. The American Government would contemplate a change of neighbors with extreme uneasiness. Due balance on their borders was not less desirable to Americans than the balance of power in Europe was to Englishmen. Jefferson wrote: “We wish to be neutral, and we will be so if they will execute the treaty fairly and attempt no conquests adjoining us.” Other dominions of Spain, he declared, left them room for conquests. “If war takes place, we would really wish to be quieted on these two points, offering in return an honorable neutrality. More than this they are not to expect.”