The United States, who led the way in the overthrow of the feudal doctrine of perpetual allegiance, are among the last to indicate how their own citizens may elect another nationality. The papers submitted herewith indicate what is necessary to place us on a par with other leading nations in liberality of legislation on this international question. We have already in our treaties assented to the principles which would need to be embodied in laws intended to accomplish such results. We have agreed that citizens of the United States may cease to be citizens and may voluntarily render allegiance to other powers. We have agreed that residence in a foreign land, without intent to return, shall of itself work expatriation. We have agreed in some instances upon the length of time necessary for such continued residence to work a presumption of such intent. I invite Congress now to mark out and define when and how expatriation can be accomplished; to regulate by law the condition of American women marrying foreigners; to fix the status of children born in a foreign country of American parents residing more or less permanently abroad, and to make rules for determining such other kindred points as may seem best to Congress.

In compliance with the request of Congress, I transmitted to the American minister at Madrid, with instructions to present it to the Spanish Government, the joint resolution approved on the 3d of March last, tendering to the people of Spain, in the name and on the behalf of the American people, the congratulations of Congress upon the efforts to consolidate in Spain the principles of universal liberty in a republican form of government.

The existence of this new Republic was inaugurated by striking the fetters from the slaves in Porto Rico. This beneficent measure was followed by the release of several thousand persons illegally held as slaves in Cuba. Next, the Captain-General of that colony was deprived of the power to set aside the orders of his superiors at Madrid, which had pertained to the office since 1825. The sequestered estates of American citizens, which had been the cause of long and fruitless correspondence, were ordered to be restored to their owners. All these liberal steps were taken in the face of a violent opposition directed by the reactionary slave-holders of Havana, who are vainly striving to stay the march of ideas which has terminated slavery in Christendom, Cuba only excepted. Unhappily, however, this baneful influence has thus far succeeded in defeating the efforts of all liberal-minded men in Spain to abolish slavery in Cuba, and in preventing the promised reform in that island. The struggle for political supremacy continues there.

The proslavery and aristocratic party in Cuba is gradually arraigning itself in more and more open hostility and defiance of the home government, while it still maintains a political connection with the Republic in the peninsula; and although usurping and defying the authority of the home government whenever such usurpation or defiance tends in the direction of oppression or of the maintenance of abuses, it is still a power in Madrid, and is recognized by the Government. Thus an element more dangerous to continued colonial relations between Cuba and Spain than that which inspired the insurrection at Yara--an element opposed to granting any relief from misrule and abuse, with no aspirations after freedom, commanding no sympathies in generous breasts, aiming to rivet still stronger the shackles of slavery and oppression--has seized many of the emblems of power in Cuba, and, under professions of loyalty to the mother country, is exhausting the resources of the island, and is doing acts which are at variance with those principles of justice, of liberality, and of right which give nobility of character to a republic. In the interests of humanity, of civilization, and of progress, it is to be hoped that this evil influence may be soon averted.

The steamer Virginius was on the 26th day of September, 1870, duly registered at the port of New York as a part of the commercial marine of the United States. On the 4th of October, 1870, having received the certificate of her register in the usual legal form, she sailed from the port of New York and has not since been within the territorial jurisdiction of the United States. On the 31st day of October last, while sailing under the flag of the United States on the high seas, she was forcibly seized by the Spanish gunboat Tornado, and was carried into the port of Santiago de Cuba, where fifty-three of her passengers and crew were inhumanly, and, so far at least as relates to those who were citizens of the United States, without due process of law, put to death.

It is a well-established principle, asserted by the United States from the beginning of their national independence, recognized by Great Britain and other maritime powers, and stated by the Senate in a resolution passed unanimously on the 16th of June, 1858, that--American vessels on the high seas in time of peace, bearing the American flag, remain under the jurisdiction of the country to which they belong, and therefore any visitation, molestation, or detention of such vessel by force, or by the exhibition of force, on the part of a foreign power is in derogation of the sovereignty of the United States. In accordance with this principle, the restoration of the Virginius and the surrender of the survivors of her passengers and crew, and a due reparation to the flag, and the punishment of the authorities who had been guilty of the illegal acts of violence, were demanded. The Spanish Government has recognized the justice of the demand, and has arranged for the immediate delivery of the vessel, and for the surrender of the survivors of the passengers and crew, and for a salute to the flag, and for proceedings looking to the punishment of those who may be proved to have been guilty of illegal acts of violence toward citizens of the United States, and also toward indemnifying those who may be shown to be entitled to indemnity. A copy of a protocol of a conference between the Secretary of State and the Spanish minister, in which the terms of this arrangement were agreed to, is transmitted herewith.

The correspondence on this subject with the legation of the United States in Madrid was conducted in cipher and by cable, and needs the verification of the actual text of the correspondence. It has seemed to me to be due to the importance of the case not to submit this correspondence until the accurate text can be received by mail. It is expected shortly, and will be submitted when received.

In taking leave of this subject for the present I wish to renew the expression of my conviction that the existence of African slavery in Cuba is a principal cause of the lamentable condition of the island. I do not doubt that Congress shares with me the hope that it will soon be made to disappear, and that peace and prosperity may follow its abolition.

The embargoing of American estates in Cuba, cruelty to American citizens detected in no act of hostility to the Spanish Government, the murdering of prisoners taken with arms in their hands, and, finally, the capture upon the high seas of a vessel sailing under the United States flag and bearing a United States registry have culminated in an outburst of indignation that has seemed for a time to threaten war. Pending negotiations between the United States and the Government of Spain on the subject of this capture, I have authorized the Secretary of the Navy to put our Navy on a war footing, to the extent, at least, of the entire annual appropriation for that branch of the service, trusting to Congress and the public opinion of the American people to justify my action.

Assuming from the action of the last Congress in appointing a Committee on Privileges and Elections to prepare and report to this Congress a constitutional amendment to provide a better method of electing the President and Vice-President of the United States, and also from the necessity of such an amendment, that there will be submitted to the State legislatures for ratification such an improvement in our Constitution, I suggest two others for your consideration: