GIO

I have searched for these documents and anything else available that would give the information you are looking for. The only documents I find directly related to the bills are the references in the Congressional Record. The minutes and other documents of the Committee on Pensions were not published and are only available in the National Archives at the Center for Legislative Archives. You can see a description of the records that are available for this committee, along with descriptions of what type of information is in the records, at https://www.archives.gov/legislative/guide/house/chapter-06.html#CmtPensions1880

You can see the contact information and information for accessing these records at https://www.archives.gov/legislative/research

I did find one record that provides a little more information about William C. Clark's military career in Ancestry.com. The source is the Roster & Record of Iowa Soldiers in the War of Rebellion, and I have attached the record to this response.

I also found a certificate for a pension William was awarded for wounds received in the Battle of Corinth, but I haven't found a pension record for his widow. The pension record for a widow would appear in the "Dependent" column with the veteran's name and a (W) beneath. The pension certificate for William is numbered 25327, and apparently that number is useful for identifying other related documents, but I'm not familiar enough with the system to know exactly how that works. 

I've also attached a short document summarizing the Battle of Corinth, which is where William C. Clark was wounded. 

Information on researching military service records at the National Archives is available at https://www.archives.gov/publications/prologue/2002/fall/military-records-overview.html

Information on requesting military records is available at https://www.archives.gov/research/order/research/order/order-vets-records

More detailed information on researching military records for history or genealogy purposes is available at https://www.archives.gov/research/military 

I haven't really found any information on birth or death dates except for the birth year given in the Civil War record posted here. I found a marriage record for a William C. Clark and Martha E. Mitchell, but the record is too sparse to know if this is the same couple, and I don't have a record of Martha E. Clark's maiden name from another source. One of the problems I've had with searching for information on these to names is that the names are so common they tend to come up with many false or ambiguous leads.  

I found some census records that show a William C. Clark (born in 1838, but in January, not October) married to a Mary E. Clark and living in Dallas, Iowa, which is very close to Knoxville, Iowa. They seemed close enough to possible be the same couple, but in the 1920 census William is listed as a widow and Mary no longer appears in  the census record, so the similarities are just a coincidence.

I don't know if you have consulted a genealogist, but if not, someone with expertise in searching this type of information might be able to provide more leads or suggestions. Like the NARA records, some of this information may be available somewhere, but not necessarily on line.

I hope this information has been of some help. Please let me know if any of these links don't work or if you need further assistance.

Bobby Griffith
Lead Government Information Reference Associate 
Sycamore Library University of North Texas Libraries

bobby.griffith@unt.edu