I would suggest you take a look at the newspapers published in the counties that furnished troops to the 129th Indiana. Newspapers of the day often published lengthy, and quite detailed, accounts of engagements, camp life, etc.

The 129th Indiana was organized at Kendallsville and Michigan City, IN, so a good place to start would be in the Laporte and Lake County, Indiana papers. You can obtain these by interlibrary loan via your local public library. To find the extant papers covering the Civil War period, you can check at the Indiana State Library newspaper index:

http://www.statelib.lib.in.us/www/isl/indiana/newspaper/hold.html

Other potential sources are in the Indiana Historical Society and the regimental correspondence microfilm for the 129th IVI at the Indiana State Archives. Furthermore, checking the holdings of the historical societies in the counties that provided troops to the 129th IVI could be potentially fruitful as well.

Regards,

Mark Jaeger