Chapter 2 - One Year of Military Service during Peacetime (INA 328)
A person who has served honorably in the U.S. armed forces for one year at any time may be eligible to apply for naturalization, which is sometimes referred to as “peacetime naturalization.”  While some of the general naturalization requirements apply to qualifying members or veterans of the U.S. armed forces seeking to naturalize based on one year of service,  other requirements may not apply or are reduced.
The applicant must establish that he or she meets all of the following criteria in order to qualify:
The applicant must be 18 years of age or older.
The applicant must have served honorably in the U.S. armed forces for at least one year.
The applicant must be a lawful permanent resident (LPR) at the time of examination on the naturalization application.
The applicant must meet certain residence and physical presence requirements.
The applicant must demonstrate an ability to understand English including an ability to read, write, and speak English.
The applicant must demonstrate knowledge of U.S. history and government.
The applicant must demonstrate good moral character for at least five years prior to filing the application until the time of his or her naturalization.
The applicant must have an attachment to the principles of the U.S. Constitution and be well disposed to the good order and happiness of the U.S. during all relevant periods under the law.
Qualifying military service is honorable active or reserve service in the U.S. Army, Navy, Marine Corps, Air Force, Coast Guard, or service in a National Guard unit. Honorable service means only service in the U.S. armed forces that is designated as honorable service by the executive department under which the applicant performed that military service.
Both “Honorable” and “General-Under Honorable Conditions” discharge types qualify as honorable service for immigration purposes. Other discharge types, such as “Other Than Honorable,” do not qualify as honorable service.
Honorable service as a member of the National Guard is limited to service in a National Guard unit during such time as the unit is federally recognized as a reserve component of the U.S. armed forces. This applies to applicants for naturalization on the basis of one year of military service. 
An applicant who files on the basis of one year of military service while he or she is still serving in the U.S. armed forces or within six months of an honorable discharge is exempt from the residence and physical presence requirements for naturalization. 
An applicant who files six months or more from his or her separation from the U.S. armed forces must have continuously resided in the United States for at least five years. In addition, the applicant must have been physically present in the United States for at least 30 months out of the five years immediately preceding the date of filing the application.  However, any honorable service within the five years immediately preceding the date of filing the application will be considered towards residence and physical presence within the United States. 
An applicant with military service who does not qualify on the basis of one year of military service  may be eligible under another non-military naturalization provision. The period that the applicant has resided outside of the United States on official military orders does not break his or her continuous residence. USCIS will treat such time abroad as time in the United States. 
3. [^] See INA 328. The National Guard and Reserve service requirements under INA 329 differ from those under INA 328. See Chapter 3, Military Service during Hostilities (INA 329), Section C, National Guard Service [12 USCIS-PM I.3(C)].
8. [^] Special provisions also exist regarding the “place of residence” for applicants who are serving in the U.S. armed forces but who do not qualify for naturalization through the military provisions. See 8 CFR 316.5(b). See Part D, General Naturalization Requirements, Chapter 6, Jurisdiction, Place of Residence, and Early Filing [12 USCIS-PM D.6].
8 CFR 316.5(b)(6) - Residence for certain spouses of military personnel
8 CFR 316.6 - Physical presence for certain spouses of military personnel
8 U.S.C. 1443a - Overseas naturalization for service members and their qualifying spouses and children
INA 101(f) - Definition of good moral character
Legislation Assisting Military Members and their Families Obtain Immigration Benefits
Appendix: Legislation Assisting Military Members and their Families Obtain Immigration Benefits
The table below provides some of the major legislative amendments that have aimed at assisting qualified military personnel and their eligible family members to become U.S. citizens or to acquire other immigration benefits, or both.
Act of May 9, 1918 (40 Stat. 512)
Modifications of 1918 Act 
Second War Powers Act of March 27, 1942 (amending Nationality Act of 1940)
Legislation of December 7, 1942 (amending Nationality Act of 1940)
Act of June 1, 1948; Immigration and Nationality Act
Lodge Act, June 30, 1950 (64 Stat. 316)
Korean Hostilities; Act of June 30, 1953 (Pub. L. 86)
Vietnam Hostilities Act of October 24, 1968 (82 Stat. 1343)
Grenada 15 Executive Order 12582 (February 2, 1987) 
Naturalization of Natives of the Philippines (WWII Service), Sec. 405 of Pub. L. 101-649
Hmong Veterans’ Naturalization Act of 2000
National Defense Authorization Act for Fiscal Year 2004 (Pub. L. 108-136)
National Defense Authorization Act for Fiscal Year 2008 (Pub. L. 110-181)
Kendell Frederick Citizenship Assistance Act (KFCAA) (Pub. L. 110-251)
Military Personnel Citizenship Processing Act (MPCPA) (Pub. L. 110-382)
1. [^] See Application of Campbell, 5 F.2d 247 (E.D. Wash. 1925). See Op. Sol. of Labor, Jan, 1926, CO file 79/9.
2. [^] See Acts of July 19 and November 6, 1919, May 26, 1926, March 4, 1929, May 25, 1932, June 24, 1935, August 23, 1937, June 21, 1939, December 7, 1942.
3. [^] See Executive Order 12582, signed on February 2, 1987 (52 FR 3395, February 4, 1987). In consideration of Matter of Reyes, 910 F. 2d 611 (9th Cir. 1990), Executive Order 12582 was revoked by Executive Order 12913, effective February 2, 1987, (59 FR 23115, May 4, 1994).
4. [^] See Sec. 1703 of PL 108-136.
5. [^] See Sec. 673 of PL 110-181.
POLICY ALERT - Defining “Residence” in Statutory Provisions Related to CitizenshipAugust 28, 2019
U.S. Citizenship and Immigration Services (USCIS) is issuing policy guidance in the USCIS Policy Manual to address requirements for “residence” in statutory provisions related to citizenship, and to rescind previous guidance regarding children of U.S. government employees and members of the U.S. armed forces employed or stationed outside the United States. This guidance becomes effective October 29, 2019.
POLICY ALERT - Comprehensive Citizenship and Naturalization Policy GuidanceJanuary 07, 2013
USCIS is issuing updated and comprehensive citizenship and naturalization policy guidance in the new USCIS Policy Manual.