The three major time periods to consider are:
1. Pre-1867 - Records centrally maintained at the Vienna War Archives. These records include soldiers from the entire Empire including individuals from Austria, the Czech regions, Galicia, and all of Hungary.
2. 1867 to 1918 - Records maintained by Austria and by Hungary separately. Austria kept the records for the regions they directly administered, including Galicia and the Czech regions of Bohemia and Moravia. Hungary kept those for everyone in their kingdom, which included the Slovaks and other slavs within their borders. By treaty, these records were to be sent to the successor countries but there is a lot of conflicting information as to what has happened to these records (see section below on Czech Military Records).
3. Post-1918 - Records maintained by the states of Czechoslovakia (1st and 2nd Republic) and Slovakia (1st Republic) as well as the other successor nations of Poland, Yugoslavia, Romania, the Ukraine, and various countries formed after Yugoslavia was broken up.
Grundbuchblätter Records (personnel sheets)
Once you have determined your ancestor’s regiment, you can look for his personnel records. The information in personnel records includes the name of the soldier, birth year and location, marital status, civilian occupation, religion, and dates of service, description of duties, promotions if any and date of discharge.
From 1820 until 1869, individual personnel sheets for all the troops in the Empire were kept in books called Grundbuchblätter in Vienna. After 1869, these records were only kept for the Austrians and personnel from the regions they administered as described earlier.
The Grundbuchblätter records are listed by regimental number and then by class year. They are not indexed alphabetically by surname. Soldiers are listed starting with the officers, cadets and finally the enlisted men. To find an individual soldier, it is necessary to review all the records for a given class year.
The Kriegs Archive will do a search of their records for a fee or you can hire a private reseacher to do a search of these records. But they are also available on microfilm from the Family History Library on 2,884 rolls of film. Now, a bit of a warning about using these FHL films, they are not well cataloged. The film titles of the earliest records list the years covered, but the later films only list Heft (book) numbers, which are not a very useful guide. In addition, many of the film titles in the FHL catalog contain errors as to the years covered. Some indicate that they only cover the years from 1820 until 1860.
However, in most cases, the records for the 1860s are actually covered in those films. I’ve contacted the LDS about this and have had them change the titles for some films, including all the ones for the Hussars. But given these problems, it is best to order several of the films in each regimental series to make sure you get the years wanted. The easiest way to search through the film is to go the records for the birth year of your ancestor (see template below).
Then look though the records for that year (and several years on both sides if you don’t find it immediately). As mentioned, the Grundbuchblätter records by regimental number cover all soldiers in the Empire. But additional Grundbuchblätter records exist for soldiers from the eight states within what is now modern Austria (Wien, Niederösterreich, Oberösterreich, Steiermark, Kärnten, Salzburg, Tirol, and Vorarlberg). They are kept at the Kriegs Archive in Vienna.
The records cover Austrian solders from ~1820 to the end of WWI and they are organized alphabetically by the names of the soldiers within each individual state.10 The records are on 616 rolls of film available from the FHL. Czech Military Records Additional military records for soldiers coming from the Czech regions of Bohemia, Moravia and Silesia, are located at the Kreigs Archive in Vienna for the years from 1820 to 1864. Personnel sheets for Czech soldiers can be found in records called Grundbuchblätter Diverse: Bohmen, Mahren, Schlesien.
These records are organized alphabetically by the soldier’s names and are available from the FHL on 685 rolls of film or they can be obtained by a private search in the archive described above. The Director of the Kriegs Archive in Vienna, Christoph Tepperberg, has written the following statement about the records after 1864 for the Czech regions: “According to the Saint-Germain peace treaty of 1919, all Grundbuchsblätter of the years of birth 1865-1900 for soldiers outside the new Austrian Republic had to remain in, or to be surrendered to, the “successor states”. Therefore the Kriegsarchiv keeps from these age-classes only the personnel files for soldiers from the territory of today's Austrian Republic. In the successor states of the AustroHungarian Empire, the majority of these files (have) been lost.
For the Czech Republic, the Grundbuchsblätter of the years of birth 1887-1900 have been kept in the repository for military personnel files in Tyrnau (Trnava, Slovakia), where most of them were destroyed, while the remainders and the files of the age classes 1865-1886 are preserved in the Czech Historical Military Archives in Prague.” 11 Unfortunately, I do not believe the records in Prague have been filmed by the LDS, but you can hire the archives or other private researchers to do a search for you . Additional types of Czech military records are well described at Czechfamilytree.com