Chris:

Thinking about this a bit more, it is really going to be like looking for a needle in a haystack to try to find what town your great-grandfather was born in. I think that if you know yout g-g-grandfather's name and you suspect he was in the Mexican calvary that may be a more fruitful avenue to take.

Another alternative is to pull the "informaciones matrimoniales" film for your great-grandfather's first marriage. These often list grandparents as part of the due diligence to determine lack of cosanguinity.

From the familysearch.org site:
http://www.familysearch.org/eng/search/rg/guide/Mexico18.asp

Military Records of Genealogical Value

The following records include information on most soldiers and can be useful in researching your family:

* Hojas de servicios (Service records). Lists of officers’ name, birth date, birthplace, family information, and military ranks and assignments.
* Expedientes personales (Personal petition files). Personal requests by servicemen such as their petitioning for military advancements after citing their military record. The files may include a number of documents of genealogical interest, such as family baptismal and marriage certificates.
* Listas de quintas o conscripciones (Conscription lists). Lists of new recruits and in some cases a census of all males eligible for military service. The town or municipal archives (archivo de ayuntamiento) sometimes house these records.
* Filiaciones (Enlistments). Lists of common soldiers in the military, excluding officers. Enlistments include the soldiers’ name, birth date and birthplace, parents’ names, residence, religion, marital status, and physical description. They may also list the soldier’s military history. Enlistments are less likely than service sheets to be indexed.
* Padrones and listas de revistas (Census records). Censuses of military men and their families were often taken in various areas. The census records may include all the citizens who were served and protected by the military outpost.

For more information on the military records of Mexico, including where the records are found, see:

Ryskamp, George R. Tracing Your Hispanic Heritage. Riverside, Calif.: Hispanic Family History Research, 1984, pp. 591-632. (FHL book 946 D27r; computer number 0256085.)

Locating Other Military Records

Records of military service in Mexico were kept by several government agencies. Some of these records have been centralized at the Archivo General de la Nacion and the Archivo Histórico Militar Mexicano. Others can be found in different state archives as well as in the municipio archives (archivos del ayuntamiento). The Family History Library has some military records that cover the 1500s to 1900s.

The Archivo General de la Nacíon has several collections that contain valuable military records. These collections can be searched in the Archivo Histórico Militar (Historical Military Archive). Some of these collections are:

* Guerras y Pensiones (wars and pensions). These date from 1793 to 1900 and contain petitions for pensions from families who had soldiers who died in the war. These include servicemen’s name, spouse and children, date and place of birth and marriage, and place of residence.
* Listas de Revistas (list of musters). From this collection you can find the servicemen’s name, place of residence, age, civil statues, race, years in the service, and number of family members.
* Méritos y Servicios (merits and services records). These records start in 1524 and continue to 1634. They contain genealogies, biographies, names of soldiers, and occasionally their date and place of birth.

Another archive that has military records but is difficult to access is the Archivo de la Secretaría de la Defensa Nacional (Archive of the Secretary of National Defense) in Mexico City. Some of the collections include:

* Registros de Comisiones Militares (registers of military comissions).
* Hojas de Servicio Militar (military service records).
* Cancelados (files on former officers)

These records have extensive information on the soldiers and officers and their families. In order to visit this archive you need a letter of recommendation and the archive’s permission to do research.

Another military record in Mexico is the Cartillas del Servicio Militar Nacional (cards of conscripts of the national military service), which covers the last century to the present and lists persons from 18 to 48 years old. These cards are issued to all who enter the military and include a photo of the conscripted and his full name, age, date and place of birth, parents, and civil status. These records can be found either in the Ayuntamientos (municipio offices) or the Department of the Secretary of National Defense.

The above collections are only a few of many that are found throughout Mexico. Always make sure you know the history of the area in which your ancestor served, and find out what archives are available for that area and what records they contain.