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].