BAUER, Chief Judge.

The constitution empowers Congress "[t]o establish an uniform Rule of Naturalization." Article I, sec. 8, cl. 4. Any alien who seeks to acquire the "precious right" of American citizenship must meet all the requirements fixed by Congress. Schneiderman v. United States, 320 U.S. 118, 122 131, 63 S.Ct. 1333, 1335 1339, 87 L.Ed. 1796 (1943). One of the requirements Congress established for citizenship is entry into the United States by means of a legally procured immigration visa. Section 13 of the Displaced Persons Act of 1948, Pub.L. No. 80-774, ch. 647, 62 Stat. 1009, as amended by Pub.L. No. 81-555, ch. 262, 64 Stat. 219 (1950), provides that any individual who advocated or assisted in the persecution of persons because of race, religion or national origin is ineligible to obtain a visa. In the judgment appealed from here, the district court revoked Michael Schmidt's citizenship and canceled his certificate of naturalization pursuant to 8 U.S.C. § 1451(a) of the Immigration and Nationality Act. The district court found that because Schmidt served as an armed guard with the Nazi "Death's Head Battalion" at the Sachsenhausen concentration camp during World War II, he was ineligible to receive a visa. The court concluded that, because Schmidt's visa was invalid, he did not have lawful permission to enter the United States, and thus his subsequent naturalization was procured unlawfully under section 316(a)(1) of the Immigration and Nationality Act. 8 U.S.C. § 1427(a)(1) (1982). For the following reasons, we affirm.

I.

Michael Schmidt was born in Scharosch, Romania, of German parentage. In June, 1943, he was inducted into the German Army as a private and assigned to serve at the Sachsenhausen concentration camp near Oraneinburg, Germany. In the district court, the Government presented extensive evidence concerning the history of the Nazi regime and its plan to exterminate systematically individuals who disagreed with its policies, as well as groups it considered to be racially and socially inferior. The Nazis used concentration camps to carry out the Third Reich's plan to exterminate enemies or to exploit them through forced labor. The Gestapo, the Nazi secret police force, arrested and detained all persons thought to be enemies of the state. Those held in this manner could be incarcerated without trial for indefinite periods of time.

During Schmidt's service at Sachsenhausen, the camp was the second largest Nazi concentration camp after Auschwitz. Among those incarcerated there were Jews, Gypsies, Jehovah's Witnesses, certain Eastern European ethnics, political dissidents, homosexuals, and various individuals considered social "misfits," including beggars, vagrants, and the mentally ill. Each category of prisoner was forced to wear a colored triangle on the outside of its uniform: Jews, yellow; political prisoners, red; social misfits, black/brown; Jehovah's Witnesses, violet; homosexuals, pink. At the height of its operation, Sachsenhausen contained approximately 50,000 prisoners.

The "Death Head's Battalion" — the SS-Totenkopf Sturmbann — was organized as part of the armed SS for the purpose of guarding Nazi concentration camps. The military command assigned Schmidt to guard prisoners on forced labor crews outside Sachsenhausen. His duties included escorting prisoners to and from work sites, counting prisoners before returning them to the concentration camp, and keeping prisoners in formation. Schmidt wore on his SS uniform the skull and crossbones insignia of the Death Head's Battalion. He carried a rifle and ammunition and had orders to shoot at prisoners who attempted to escape. Because concentration camp guards were not permitted to enter the camps themselves, Schmidt was confined to patrol outside the camp wall. Although there is no evidence that Schmidt personally killed prisoners, it has been documented that during the period he served at Sachsenhausen, two Jews were intentionally murdered and at least thirteen prisoners were executed by being shot through the nape of the neck.

In addition, tens of thousands died in Sachsenhausen as a result of starvation, exhaustion, beatings, exposure, disease, and medical experimentation. The grim history of Sachsenhausen has been well-documented by historians and tribunals that have tried Nazi war criminals. For example, the Government presented transcripts of German criminal proceedings against various individuals found guilty of committing atrocities at Sachsenhausen: camp leaders Hermann Sorge and August Hohn; barracks leader Wilhelm Karl Ferdinand; and medical doctors Heinz Baumkotter, Alois Gaberle, and Otto Adam. In addition, the Government presented the testimony of a historian, Charles W. Syndor, President of Emory and Henry College in Emory, Virginia, who has made a career of studying the Nazi regime and its concentration camps. Syndor's testimony catalogued the mass killings, subhuman living conditions, and bizarre medical experiments that occurred in Sachsenhausen and its environs. Finally, the Government submitted transcribed interrogations of Sachsenhausen guards and the testimony of camp survivors who witnessed beatings, killings, and indescribably cruel treatment of prisoners.

Schmidt continued to serve as an armed guard at Sachsenhausen until at least September, 1944. He then served in the Third Battalion of the 38th SS Armored Infantry Division, "Goetz von Berlichingen," and was wounded in combat in Lorraine, France on November 28, 1944. He remained in military hospitals until he became a British prisoner of war. He was released on July 8, 1946.

Schmidt made his way to the United States under the authority of the Displaced Persons Act of 1948 ("DPA"). Congress enacted the DPA to accommodate the large number of European refugees wishing to emigrate to the United States after World War II. A person seeking to obtain an immigration visa under the DPA was required to obtain a designation of "displaced person" status as defined by the Constitution of the International Refugee Organization of the United Nations ("IRO"). 62 Stat. 3037-55 (1946). Annex I, Part II of the IRO Constitution provided that war criminals and others who "assisted the enemy in persecuting civil populations of countries" were not "the concern" of the IRO. Id. at 3051-52. These individuals thus were excluded from the definition of "displaced persons" under the DPA.

After checking the applicant's background, a case analyst from the Displaced Persons Commission ("DPC") issued a report certifying that the applicant was a person eligible for admission into the United States. The analyst then forwarded the applicant's file to the appropriate American consulate. A vice-consul reviewed the visa application and other documents in the applicant's file, including the preliminary IRO certification and the DPC report. The vice-consul also interviewed the applicant and, if the applicant met the criteria of the DPA and other immigration laws, the vice-consul issued a visa.

After living in Germany and Austria for several years following the war, Schmidt applied for a determination from the DPC that he was a displaced person eligible to emigrate to the United States. On his application, Schmidt indicated to the DPC that he was conscripted into the "German Army, Waffen-SS `Goetz von Berlichingen,'" but he did not indicate his service as a guard at Sachsenhausen. Based on Schmidt's representations in his questionnaire, on February 28, 1952, DPC case analyst John F. Zipf, Jr. certified Schmidt as a displaced person eligible for a visa. Paul B. Lanius, Jr., the American Vice-Consul in Salzburg, Austria, issued Schmidt a visa in April, 1952. Schmidt entered the United States pursuant to this visa on May 24, 1952.

On March 1, 1968, Schmidt filed an application to become a United States citizen. Question 7 of the application form required him to list "present and past membership in every organization, association, fund, foundation, party, club, society, or similar group in the United States and in any other place, and your foreign military service." Schmidt entered his military service in the German army from 1943 to 1945, but did not indicate that he had served as an armed guard at Sachsenhausen from June, 1943 to September, 1944. On April 2, 1968, the United States District Court for the Northern District of Illinois issued a certificate of naturalization granting Schmidt United States citizenship.

Schmidt lived a quiet life in the Chicago area, where he worked as a janitor until his retirement. Following a determination by the Criminal Division of the Office of Special Investigations of the United States Department of Justice that there was good cause to revoke Schmidt's citizenship, the Government filed a complaint in federal district court on November 2, 1988. The court ordered Schmidt's citizenship revoked and, in February, 1990, Schmidt surrendered his certificate of naturalization to the Attorney General of the United States. This appeal followed.

II.

At issue is whether, under section 13 of the Displaced Persons Act, Schmidt's service in the SS as a guard at Sachsenhausen concentration camp rendered him ineligible to obtain a visa, in that his activities constituted assistance in the persecution of persons because of race, religion or national origin. The district court believed it did, and granted summary judgment on that basis. Summary judgment is appropriate in denaturalization proceedings when there are no genuine issues of triable fact. United States v. Dercacz, 530 F. Supp. 1348, 1350-51 (E.D.N.Y. 1982). We review the matter de novo to determine whether the record as a whole establishes that the Government was entitled to judgment as a matter of law.

Citizenship is procured illegally any time the applicant has failed to comply with "all the congressionally imposed prerequisites to the acquisition of citizenship." Fedorenko v. United States, 449 U.S. 490, 506, 101 S.Ct. 737, 747, 66 L.Ed.2d 686 (1981) (citing Afroyim v. Rusk, 387 U.S. 253, 267 n. 23, 87 S.Ct. 1660, 1667 n. 23, 18 L.Ed.2d 757 (1967)). Section 316(a)(1) of the Immigration and Nationality Act of 1952, 8 U.S.C. § 1427, requires that the person seeking naturalization has been "lawfully admitted for permanent residence," that is, possess a valid visa. In denaturalization proceedings for illegal acquisition of citizenship, an individual's failure to enter the United States lawfully by means of a valid immigration visa, a condition precedent to naturalization, commands denaturalization. Further, section 13 of the DPA mandates that an individual is ineligible for a visa if a member of a specifically excluded category of persons: those who assisted in persecution. See, e.g., United States v. Leprich, 666 F. Supp. 967, 969 (E.D.Mich. 1987) ("[B]ecause Leprich was a concentration camp guard, he was ineligible for the visa he received and his citizenship was illegally procured.")

The district court granted summary judgment in favor of the Government on the ground that Schmidt had "in fact assisted in the persecution of persons because of their race, religion or national origin by serving as an armed guard at Sachsenhausen concentration camp." United States v. Schmidt, No. 88-C-9475, slip op. at 21, 1990 WL 6667 (N.D.Ill. January 3, 1990). Schmidt argues that the district court erred in several respects. The essence of his argument is that the court improperly focused upon his status as a member of the "Death Head's Battalion," rather than upon his specific conduct.

Schmidt first maintains that the court failed to consider that he involuntarily joined the SS. In Fedorenko, the Supreme Court stated that "[u]nder traditional principles of statutory construction, the deliberate omission of the word `voluntary' from the DPA compels the conclusion that the statute made all who assisted in the persecution of civilians ineligible for visas." 449 U.S. at 512, 101 S.Ct. at 750 (emphasis in original). The Court rejected the distinction between voluntary and involuntary service for DPA purposes, and held that service as an armed guard in a concentration camp constitutes assistance to the enemy under the DPA as a matter of law. Id. at 514, 101 S.Ct. at 751. Therefore, Schmidt's involuntary service argument is meritless.

Schmidt also argues that he personally did not commit atrocities against the Sachsenhausen prisoners. He contends that because armed guards were not permitted to enter the camp, he had no knowledge of the persecution occurring within Sachsenhausen's walls. Whether or not Schmidt personally engaged in acts of violence, however, does not affect our conclusion that he assisted in persecution. Concerned that concentration camp survivors might become ineligible for visas because of "assistance" they had provided to their Nazi captors in the death camps, the Fedorenko Court drew a continuum of conduct ranging from passive acceptance to active, personal participation. The Court distinguished between a person who only cut the hair of fellow inmates before they were killed and an armed guard who shot a fleeing inmate, finding that the former should not be found to have assisted in the persecution of civilians, but that the latter should. Id. at 512 n. 34, 101 S.Ct. at 750 n. 34. It is more difficult to determine whether conduct falling elsewhere on the continuum may be considered persecution. The difficulty of the problem is magnified by the task of determining the contribution of a single individual to the collective wrong-doing of a nation or group.

Whatever close questions may be presented by the application of the Fedorenko continuum to other factual situations, it is clear that service as an armed concentration camp guard constitutes assisting in persecution under the DPA. In Schellong v. INS, 805 F.2d 655 (7th Cir. 1986), cert denied, 481 U.S. 1004, 107 S.Ct. 1624, 95 L.Ed.2d 199 (1987), we observed that "Nazi concentration camps were places of persecution; individuals who, armed with guns, held the prisoners captive and prodded them into forced labor with threats of death or capital punishment cannot deny that they aided the Nazis in their program of racial, political, and religious oppression." Id. at 661. When examined in context, the activities of an armed concentration guard must be viewed as contributing to the collective effort of the Nazis to persecute innocent civilians.

Indeed, the facts in Schmidt's case virtually are indistinguishable from those in Kulle v. INS, 825 F.2d 1188 (7th Cir. 1987), cert. denied, 484 U.S. 1042, 108 S.Ct. 773, 98 L.Ed.2d 860 (1988). Kulle also served in the Totenkopf Division of the Nazi Waffen SS. From 1942 to 1945, he was an armed guard at Gross-Rosen, a concentration camp in Silesia, now a part of Poland. Gross-Rosen was a forced labor camp, and Kulle, like Schmidt, worked along the perimeter of the camp. Kulle, like Schmidt, argued that he did not assist in persecuting prisoners "merely because he was present." Id. at 1192. Rejecting this argument, we indicated that, because the applicable statutory provision authorized deportation of anyone who "assisted" in persecution, "personal involvement in atrocities need not be proven." Id. Thus, we affirmed an order of Board of Immigration Appeals that Kulle be deported because he participated in persecution. Schmidt argues that Kulle is distinguishable because Kulle participated in the forced removal of concentration camp prisoners from Poland to Germany in mid-winter, while Schmidt guarded work parties. The distinction eludes us. Service as an armed guard equally ensured the systematic destruction of concentration camp inmates. See also United States v. Kairys, 782 F.2d 1374, 1378 (7th Cir. 1986) (" Fedorenko continues to stand for the proposition that service as an armed guard equals persecution.")

Thus, even if Schmidt personally did not participate in the brutal acts committed at Sachsenhausen, the fact of his armed, uniformed service is sufficient to establish that he assisted in persecution. In United States v. Osidach, 513 F. Supp. 51, 78-79 (E.D.Pa. 1981), appeal dismissed on defendant's death, No. 81-1956 (3rd Cir. 1981), the court concluded that an individual who served as an armed, uniformed member of the Ukrainian police during World War II was a participant in persecution for purposes of section 13 of the DPA. The Osidach court suggests, as does Schmidt, that mere membership in a group involved in persecution is insufficient to establish that an individual is a persecutor himself. Id. at 79. Even the Osidach court recognized, however, that armed, uniformed service on behalf of an occupying force constitutes a form of persecution:

The mere presence of the watchful eye of the conqueror or his deputies, coupled with the often demonstrated presence of both the means and the inclination to persistently inflict various indignities, physical abuse, injuries or even death, without notice or reason, is the personification of mental persecution, to anyone, let alone innocent civilian men, women and children reduced to various degrees of substandard mental and physical well-being.

Id. at 99.

In light of these precedents, we conclude that Schmidt assisted in persecution of persons because of race, religion or national origin as contemplated by section 13 of the DPA. He carried a gun and wore the uniform of the dreaded "Death Head's Battalion". He guarded Jews, Gypsies, Jehovah's Witnesses, Eastern European nationals, and other persecuted peoples and forced them to do the bidding of the Third Reich. Schmidt prevented these prisoners from fleeing, and subjected them to forced labor under unspeakably brutal conditions. Such employment removed Schmidt from the intended scope of those to be aided by the DPA.

III.

In affirming the district court's revocation of Schmidt's citizenship, we are mindful of the fact that Schmidt has lived in the United States for many years, and that he has raised a family and established roots in this country. At the same time, we are mindful of the fact that Schmidt entered the United States on an invalid visa and acquired that "precious right" of citizenship unlawfully. When Congress enacted the DPA, it sought to help those who had been persecuted by the enemy because of their religious, nationalistic, and ethnic identities. By excluding those who "assisted in persecution" in section 13 of the DPA, Congress intended to prevent those who contributed to the Nazi persecution of innocent civilians from obtaining visas to enter the United States as refugees. It would defeat the paramount purpose of the DPA — to assist those whose lives had been disrupted by persecution — to extend the statute's benefits to the persecutors themselves.

As we held in Kulle and the Supreme Court held in Fedorenko, an armed guard at a Nazi concentration camp is not eligible for a visa under the Displaced Persons Act. Schmidt, therefore, was not eligible for the visa he obtained pursuant to the DPA. Because he did not fulfill all of the statutory requirements for naturalization, his citizenship was illegally procured. Accordingly, the district court's entry of summary judgment revoking his citizenship and canceling his certificate of naturalization was correct as a matter of law and is, therefore,

AFFIRMED.