delivered the opinion of the Court.
The respondent was born in the Dominion of Canada. He came to the United States in 1916, and in 1925 declared his intention to become a citizen. His petition for naturalization was presented to the federal district court for Connecticut, and that court, after hearing and consideration, denied the application upon the ground that, since petitioner would not promise in advance to bear arms in defense of the United States unless he believed the war to be morally justified, he was not attached to the principles of the Constitution.. The Circuit Court of Appeals reversed the decree and directed the district court to admit respondent to citizenship. 42 F. (2d) 845.
The Naturalization Act, § 4, c. 3592, 34 Stat. 596 (U. S. C., Title 8, § 372 et seq.), provides that an alien may be admitted to citizenship in the manner therein provided and not otherwise. By § 3 of the same act, jurisdiction to naturalize aliens is conferred upon the district courts of the United States and other enumerated courts of record. U. S. C., Title 8, § 357. The applicant is required to make *614and file a preliminary declaration in writing setting forth, among other things, his intention to become a citizen of the United States and to renounce all allegiance to any foreign prince, etc. Section 4 of the act (U. S. C., Title 8, §§ 381, 382) provides:
“ Third. He shall, before he is admitted to citizenship, declare on oath in open court that he will support the Constitution of the United States, and that he absolutely and entirely renounces and abjures all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, and particularly by name to the prince, potentate, state, or sovereignty of which he was before a citizen or subject; that he will support and defend the Constitution and laws of the United States against all enemies, foreign and domestic, and bear true faith and allegiance to the same.
“ Eourth. It shall be made to appear to the satisfaction of the court admitting any alien to citizenship that immediately preceding the date of his application he has resided continuously within the United States five years at least, and within the State or Territory where such court is at the time held one year at least, and that during that time he has behaved as a man of good moral character, attached to the principles of the Constitution of the United States, and well disposed to the good order and happiness of the same. In addition to the oath of the applicant, the testimony of at least two witnesses, citizens of the United States, as to the facts of residence, moral character, and attachment to the principles of the Constitution shall be required, . . .”
Section 9 of the act, 34 Stat. 599 „(U. S. C., Title 8, § 398), requires that every final hearing upon a petition for naturalization shall be had in open court; that every final order upon the petition shall be under the hand of the court; and that “ upon such final hearing of such petition the applicant and witnesses shall be examined under *615oath before the court and in the presence of the court.” By § 11, 34 Stat. 599 (U. S. C., Title 8, § 399), it is provided that the United States shall have the right to appear in the proceeding for the purpose of cross-examining the petitioner and witnesses produced in support of the petition “ concerning any matter touching or in any way affecting his right to admission to citizenship, and shall have the right to call witnesses, produce evidence, aiid be heard in opposition to the granting of any petition in naturalization proceedings.”
By the petition for naturalization a case is presented for the exercise of the judicial power under the Constitution, to which the United States is a proper, and always a possible, adverse party. Tutun v. United States, 270 U. S. 568, 576-577.
Naturalization is a privilege, to be given, qualified or withheld as Congress may determine, and which the alien may claim as of right only upon compliance with the terms which Congress imposes. That Congress regarded the admission to citizenship as a serious matter is apparent from the conditions and precautions with which it carefully surrounded the subject. Thus, among other provisions, it is required that the applicant not only shall reside continuously within the United States for a period of at least five years immediately preceding his application, but shall make a preliminary declaration of his intention to become a citizen at least two years prior to his admission. He must produce the testimony of witnesses as to the facts of residence, moral character and attachment to the principles of the Constitution, and in open court take an oath renouncing his former allegiance and pledging future allegiance to the United States. At the final hearing in open court, he and his witnesses must be examined under oath, and the government may appear for the purpose of cross-examining in respect of “any matter touching or in any way affecting his right to *616admission,” introduce countervailing evidence, and be heard in opposition.
In specifically requiring that the court shall be satisfied that the applicant, during his residence in the United States, has behaved as a man of good moral character, attached to the principles of the Constitution of the United States, etc., it is obvious that Congress regarded the fact of good character and the fact of attachment to the principles of. the Constitution as matters of the first importance. The applicant’s behavior is significant to the extent that it tends to establish or negative these facts.
But proof of good behavior does not close the inquiry. Why does the statute require examination of the applicant and witnesses in open court and under oath, and for what purpose is the government authorized to cross-examine concerning any matter touching or in any way affecting the right of naturalization? Clearly, it would seem, in order that the court and the government, whose power and duty in that respect these provisions take for granted, may discover whether the applicant is fitted for citizenship;— and to that end, by actual'inquiry, ascertain, among other things, whether he has intelligence and good character; whether his oath to support and defend the Constitution and laws of the United States, and to bear true faith and allegiance to the same, will be taken without mental reservation or purpose inconsistent therewith; whether his views are compatible with the obligations and duties of American citizenship; whether he will upon his own part observe the laws of the land; whether he is willing to support the government in time of war, as well as in time of peace, and to assist in the defense of the country, not to the extent or in the manner that he may choose, but to such extent and in such manner as he lawfully may be ' required to do. These, at least, are matters which are of the essence of the statutory requirements, and in' respect of which the mind and conscience of the applicant *617may be probed by pertinent inquiries, as fully as the court, in the exercise of a sound discretion, may conclude is necessary.
The settled practice of the courts having jurisdiction in naturalization proceedings has, from the beginning, been in accordance with this view. In re Bodek, 63 Fed. 813; In re Meakins, 164 Fed. 334; In re Madurri, 176 Fed. 465, 466; In re Ross, 188 Fed. 685; United States v. Bressi, 208 Fed. 369, 372; Schurmann v. United States, 264 Fed. 917, 920; In re Sigelman, 268 Fed. 217. And it finds support in the decisions of this Court. As early as 1830, in Spratt v. Spratt, 4 Pet. 393, 407, Chief Justice Marshall, speaking for the Court, said:
“ The various acts upon the subject submit the decision on the right of aliens to admission as citizens to courts of record. They are to receive testimony, to compare it with the law, and to judge on both law and fact.” United States v. Schwimmer, 279 U. S. 644, 649.
With the foregoing statutory provisions and the scope of the powers and duties of the courts of first instance in respect thereof in mind, we come to a consideration of the case now before us. The applicant had complied with all the formal requirements of the law, and his personal character and conduct were shown to be good in all respects. His right to naturalization turns altogether upon the effect to be given to certain answers and qualifying statements made in response to interrogatories propounded to him,
Upon the preliminary form for petition for naturalization, the following questions, among others, appear: “ 20. Have you read the following oath of allegiance? [which is then quoted]. Are you willing to take this oath in becoming a citizen? ” " 22. If necessary, are you willing to take up arms in defense of this country? ” In response to the questions designated 20, he answered "Yes.” In response to the question designated 22, he answered, “ Yes; but I should want to be free to judge of the neces*618sity.” By a written memorandum subsequently filed, he amplified these answers as follows:
“ 20 and 22. I am willing to do what I judge to be in the best interests of my country, but only in so far as I can believe that this is not going to be against the best interests of humanity in the long run. I do not undertake to support ‘ my country, right or wrong ’ in any dispute which may arise, and I am not willing to promise beforehand, and without knowing the cause for which my country may go to war, either that I will or that I will not * take up arms in defense of this country/' however ‘ necessary ’ the war may seem to be to the Government of the day.
“ It is only in a sense consistent with these statements that I am willing to promise to ‘ support and defend ’ the Government of the United States ‘against all enemies, foreign and domestic.’ But, just because I am not certain that the language of questions 20 and 22 will bear the construction I should have to put upon it in order to be ablé to answer them in the affirmative, I have to say that I do not know that I can say ‘ Yes ’ in answer to these two questions.”
Upon the hearing before the district court on the petition, he explained his position more in detail. He said that he was not a pacifist; that if allowed to interpret the oath for himself he would interpret it as not inconsistent with his position and would take it. He then proceeded to say that he would answer question 22 in the affirmative only on the understanding that he would have to believe that the war was morally justified before he would take up arms in it or give it his moral support. He was ready to give to the United States all the allegiance he ever had given or ever could give to any country, but he could not put allegiance to the government of any country before allegiance to the will of God. He did not anticipate engaging in any propaganda against the prosecution of a war which the *619government had already declared and which it considered to be justified; but he preferred not to make any absolute promise at the time of the hearing, because of his ignorance of all the circumstances which might affect his judgment with reference to such a war. He did not question that the government under certain conditions could regulate and restrain the conduct of the individual citizen, even to the extent of imprisonment. He recognized the principle of the submission of the individual citizen to the opinion of the majority in a democratic country; but he did not believe in having his own moral problems solved for him by the majority. The position thus taken was the only one he could take consistently with his moral principles and with what he understood to be the moral principles of Christianity. He recognized, in short, the right of the government to restrain the freedom of the individual for the good of the social whole; but was convinced, on the other hand, that the individual citizen should have the right respectfully to withhold from the government military services (involving, as they probably would, the taking of human life), when his best moral judgment would compel him to do so. He was willing to support his country, even to the extent of bearing arms, if asked to do so by the government, in any war which he could regard as morally justified.
There is more to the same effect, but the foregoing is sufficient to make plain his position.
These statements of the applicant fairly disclose that he is unwilling to take the oath of allegiance, except with these important qualifications: That he will do what he judges to be in the best interests of the country only in so far as he believes it will not be against the best interests of humanity in the long run; that he will not assist in the defense of the country by force of arms or give any war his moral support unless he believes it to be morally justified, however necessary the war might *620seem to the government of the day; that he will hold himself free to judge of the morality and necessity of the war, and, while he does not-anticipate engaging in propaganda against the prosecution of a war declared and considered justified by the government, he prefers to make no promise even as to that; and that he is convinced that the individual citizen should have the right to withhold his military services when his best moral judgment impels him to do so.
Thus stated, the case is ruled in principle by United States v. Schwimmer, supra. In' that case the applicant, a woman, testified that she would not take up arms in defense of the country. She was willing to be treated on the basis of a conscientious objector who refused to take up arms in the recent war, and seemed to regard herself as belonging in that class. She was an uncompromising pacifist, with no sense of nationalism, and only a cosmic sense of belonging to the human family. Her objection to military service, we concluded, rested upon reasons other than her inability to bear arms because of sex or age; and we held that her application for naturalization should be denied upon the ground, primarily, that she failed to sustain the burden of showing that she did not oppose the principle making it a duty of citizens, by force of arms when necessary, to defend their country against its enemies. At page 650 we said:
“ That it is the duty of citizens by force of arms to defend our government against all enemies whenever necessity arises is a fundamental principle of the Constitution.
“The common defense was one of the purposes for which the people ordained and established the Constitution. . . . We need not refer to the numerous statutes that contemplate defense of the United States, its Constitution and laws by armed citizens. This Court, in the Selective Draft Law Cases, 245 U. S. 366, speaking through Chief Justice White, said (p. 378) that ‘ the very concep*621tion of a just government and its duty to the citizen includes the reciprocal obligation of the citizen to render military service in case of need. . . .’
“Whatever tends to lessen the willingness of citizens to discharge their duty to bear arms in the country’s defense detracts from the strength and safety of the Government. And their opinions' and beliefs as well as their behavior indicating a disposition to hinder in the performance of that duty are subjects of inquiry under the statutory provisions governing naturalization and are of vital importance, for if all or a large number of citizens oppose such defense the ‘ good order and happiness ’ of the United States can not long endure. And it is evident that the views of applicants for naturalization in respect of such matters may not be disregarded. The influence of conscientious objectors against the use of military force in defense of the principles of our Government is apt to be more detrimental than their mere refusal to bear arms. The fact that, by reason of sex, age or other cause, they may be unfit to serve does not lessen their purpose or power to influence others. It is clear from her own statements that the declared opinions of respondent as to armed defense by citizens against enemies of the country were directly pertinent to the investigation of her application.”
And see In re Roeper, 274 Fed. 490; Clarke’s Case, 301 Pa. 321; 152 Atl. 92.
There are few finer or more exalted sentiments than that which finds expression in opposition to war. Peace is a sweet and holy thing, and war is a hateful and an abominable thing to be avoided by any sacrifice or concession that a free people can make. But thus far mankind has been unable to devise any method of indefinitely prolonging the one or of entirely abolishing the other; and, unfortunately, there is nothing which seems to afford *622positive ground for thinking that the near future will witness the beginning of the reign of perpetual peace for which good men and women everywhere never cease to pray. The Constitution, therefore, wisely contemplating the ever-present possibility of war, declares that one of its purposes is to “ provide for the common defense.” In express terms Congress is empowered “ to declare war,” which necessarily connotes the plenary power to wage war with .all the force necessary to make it effective; and “ to raise . . . armies,” which necessarily connotes the like power to say who shall serve in them and in what way.
From its very nature, the war power, when necessity calls for its exercise, tolerates no qualifications or limitations, unless found in the Constitution or in applicable principles of international law. In the words of John Quincy Adams,—“This power is tremendous; it is’ strictly constitutional; but it breaks down every barrier so anxiously erected for the protection of liberty, property and of life.” To the end that war may not result in defeat, freedom of speech may, by act of Congress, be curtailed or denied so that the morale of the people and the spirit of the army may not be broken by seditious utterances; freedom of the press curtailed to preserve our military plans and movements from the knowledge of the enemy; deserters and spies put to death without indictment or trial by jury; ships and supplies requisitioned; property of alien enemies, theretofore under the protection of the Constitution, seized without process and converted to the public use without compensation and without due process of law in the ordinary sense of that term; prices of food and other necessities of life fixed or regulated; railways taken over and operated by the government; and other drastic powers, wholly inadmissible in time of peace, exercised to meet the emergencies of war.
*623These are but illustrations of the breadth of the power; and it necessarily results from their consideration that whether any citizen shall be exempt from serving in the armed forces of the Nation in time of war is dependent upon the will of Congress and not upon the scruples of the individual, except as Congress provides. That body, thus far, has seen fit, by express enactment, to relieve from the obligation of armed service those persons who belong to the class known as conscientious objectors; and this policy is of such long standing that it is thought by some to be beyond the possibility of alteration. Indeed, it seems to be assumed in this case that the privilege is one that Congress itself is powerless to take away. Thus it is said in the carefully prepared brief of respondent:
“ To demand from an alien who desires to be naturalized an unqualified promise to bear arms in every war that may be declared, despite the fact that he may have conscientious religious scruples against doing so in som’e hypothetical future war, would mean that such an alien would come into our citizenry on an unequal footing with the native bom, and that he would be forced, as the price of citizenship, to forego a privilege enjoyed by others. That is the manifest result of the fixed principle of our Constitution, zealously guarded by our laws, that a citizen cannot be forced and need not bear arms in a war if he has conscientious religious scruples against doing so.” '
This, if it means what it seems to say, is an astonishing statement. Of course, there is no such principle of the Constitution, fixed or otherwise. The conscientious objector is relieved from the obligation to bear arms in obedience to no constitutional provision, express or implied; but because, and only because, it has accorded with the policy of Congress thus to relieve him. The *624alien, when he becomes a naturalized citizen, acquires, with one exception, every right possessed under the Constitution by those citizens who are native bom (Luria v. United States, 231 U. S. 9, 22); but he acquires no more. The privilege of the native-born conscientious objector to avoid bearing arms comes not from the Constitution, but from the acts of Congress. That body may grant or withhold the exemption as in its wisdom it sees fit; and if it be withheld, the native-born conscientious objector cannot successfully assert the privilege. No other conclusion is compatible with the well-nigh limitless extent of the war powers as above illustrated, which include, by necessary implication, the power, in the last extremity, to compel the armed service ®f any citizen in the land, without regard to his objections or his views in respect of the justice or morality of the particular war or of war in general. In Jacobson v. Massachusetts, 197 U. S. 11, 29, this Court, speaking of the liberties guaranteed to the individual by the Fourteenth Amendment, said:
“. . . and yet he may be compelled, by force if need be, against his will and without regard to his personal wishes or his pecuniary interests, or even his religious or political convictions, to take his place in the ranks of the army of his country and risk the chance of being shot down in its defense.”
The applicant for naturalization here is unwilling to become a citizen with this understanding. He is unwilling to leave the question of his future military service to the wisdom of Congress where it belongs, and where every native born or admitted citizen is obliged to leave it. In effect, he offers to take the oath of allegiance only with the qualification that the question whether the war is necessary or morally justified must, so far as his support is concerned, be conclusively determined by reference to his opinion.
*625When he speaks of putting his allegiance to the will of God above his allegiance to the government, it is evident, in the light of his entire statement, that he means to make his own interpretation of the will of God the decisive test which shall conclude the government and stay its hand. We are a Christian people (Holy Trinity Church v. United States, 143 U. S. 457, 470-471), according to one another the equal right of religious freedom, and acknowledging with reyerence the duty of obedience to the will of God. But, also, we are a Nation with the duty to survive; a Nation whose Constitution contemplates war as well as peace; whose government must go forward upon the assumption, and safely can proceed upon no other, that unqualified allegiance to the Nation and submission and obedience to the laws of the land, as well those made for war as those made for peace, are not inconsistent with the will of God.
The applicant here rejects that view. He is unwilling to rely, as every native born citizen is obliged to do, upon the probable continuance by Congress of the long established and approved practice of exempting the honest conscientious objector, while at the same time asserting his willingness to conform to whatever the future law constitutionally shall require of him; but discloses a present and fixed purpose to refuse to give his moral or armed support to any future war in which the country may be actually engaged, if, in his opinion, the war is not morally justified, the opinion of the Nation as expressed by Congress to the contrary notwithstanding.
If the attitude of this claimant, as shown by his statements and the inferences properly to be deduced from them, be held immaterial to the question of his fitness for admission to citizenship, where shall the line be drawn? Upon what ground of distinction may we hereafter reject another applicant who shall express his willingness to re*626spect any particular principle of the Constitution or obey any future statute only upon the condition that he shall entertain the opinion that it is morally justified? The applicant’s attitude, in effect, is a refusal to take the oath of allegiance except in an altered form. The qualifications upon which he insists, it is true, are made by parol and not by way of written amendment to the oath; but the substance is the same.
It is not within the province of the courts to make bargains with those who seek naturalization. They must accept the grant and take the oath in accordance with the terms fixed by the law, or forego the privilege of citizenship. There is no middle choice. If one qualification of the oath be allowed, the door is opened for others, with utter confusion as the probable final result. As this Court said in United States v. Manzi, 276 U. S. 463, 467:
" Citizenship is a high privilege, and when doubts exist concerning a grant of it, generally at least, they should be resolved in favor of the United States and against the claimant.”
The Naturalization Act is to be construed “ with definite purpose to favor and support the Government,” and the United States is entitled to the benefit of any doubt which remains in the mind of the court as to any essential matter of fact. The burden was upon the applicant to show that his views were not opposed to “ the principle that it is a duty of citizenship, by force of arms when necessary, to defend the country against all enemies, and that [his] opinions and beliefs would not prevent or impair the true faith and allegiance required by the Act.” United States v. Schwimmer, supra, 649, 650, 653. We are of opinion that he did not meet this requirement. The examiner and the court of first instance who heard and weighed the evidence and saw the applicant and witnesses so concluded. That conclusion, if we were in *627doubt, would not be rejected except for good and persuasive reasons, which we are unable to find.
The decree of the court of appeals is reversed and that of the district court is affirmed.