Aliens serving in the US military did not gain citizenship through service alone. The naturalization of soldiers was performed under certain provisions of nationality law facilitating the naturalization of members of the US armed forces. These provisions waived the Declaration of Intention requirement and waived or reduced the residency requirement. Thus many soldiers filed petitions and were naturalized the same day.
The expedited naturalization of soldiers could have been performed at either a Federal, State or local court having jurisdiction over the soldier's military base, or a judge from any of those courts might have held "naturalization court" at the military base. In either case, one copy of the petition should be on file in the court's records. Another copy was filed with the Immigration and Naturalization Service (INS), which holds duplicate copies of all naturalizations granted after September 26, 1906.
To locate a World War I soldier's naturalization, begin by searching the Index to Naturalizations of World War I Soldiers. 1918, among the Records of the Immigration and Naturalization Service and microfilmed as M1952. Note: Not all US military bases are included on this index.
If the soldier's name appears in the index file, the index card will contain the soldier's name, date of naturalization, court of naturalization (indicated by court number), certificate number, and name of the military base to which the soldier was assigned as of that date. The court number can be converted to the name of an actual court (i.e. US District Court, Trenton, NJ) by reference to the Directory of Courts having Jurisdiction in Naturalization Proceedings.*
If the soldier's name does not appear in the index file, the researcher may file a Freedom of Information/Privacy Act request to the Headquarters, Bureau of Citizenship and Immigration Services (BCIS), Washington, D.C. 20536, using Form G-639 (identifying the soldier by name, date of birth, and place of birth). A search of BCIS records will be determine whether the alien ever naturalized anywhere in the United States, under military or any other provision of US nationality law.
*Directory of Courts Having Jurisdiction in Naturalization Proceedings, _US Department of Justice, 1963. A microfilm copy of this publication is available through the Family History Library, film #1730286.