A New Date of Birth Discovered for General Thomas Sweeny?

Brigadier-General Thomas Sweeny from Dunmanway, Co. Cork is one of the best known Irish Generals of the American Civil War. His family emigrated to the United States around 1832 when Thomas was still a boy. He enjoyed a colorful career in the military; Sweeny lost an arm at the Battle of Churubusco during the Mexican war and later served in the West prior to 1861. The early part of the war saw him serving in St. Louis, Missouri, and he also participated in the Battle of Wilson’s Creek. In January 1862 he became Colonel of the 52nd Illinois- he subsequently commanded a brigade at Shiloh and a division during the Atlanta Campaign. Arrested in 1864 for attacking his commanding officer, he was acquitted but never served at the front again. Thomas was heavily involved in the Fenian movement and was the commander of all Fenian troops during the ill-fated Fenian invasion of Canada in 1866. Placed on the army’s retired list in 1870, he died on 10th April 1892 at his home on Long Island and is buried in Green-Wood Cemetery, Brooklyn. (1)

Brigadier-General Thomas Sweeny, Army of the Tennessee

Brigadier-General Thomas Sweeny, Army of the Tennessee

I recently delivered a lecture on Cork people and the American Civil War to the Cork Genealogical Society when I was handed a fascinating document by Pat McCarthy of Dunmanway. Pat had scanned the local Catholic baptismal records for November and December 1817, which have an intriguing entry on the last line. It records the baptism of ‘Thomas of William Sweeny [and] Honora Sweeny’, along with the name of two witnesses and where the family were from, the ‘Green.’ The Green remains a well-known part of Dunmanway. William and Honora are known to be the Generals parents- it was Honora who would take her children across the Atlantic some five years after her husband’s death.

Dunmanway Baptismal record for November and December 1817, with Thomas Sweeny listed at bottom (Pat McCarthy)

Dunmanway Baptismal records for November and December 1817, with Thomas Sweeny listed at bottom (Pat McCarthy)

What is most interesting about this document is its date. Thomas Sweeny’s date of birth is almost always recorded as 25th December 1820. This baptismal record suggests that Thomas may have been three years older than he said he was (or thought he was). Alternatively, could this be an older brother of the General who did not survive infancy, with the name being used again for a later son? Whatever the answer, Pat McCarthy’s discovery highlights the potential for revealing new detail about well-known Irish-American figures of the period through the close analysis of Irish records. I am deeply indebted to Pat for bringing this document to my attention and allowing me to reproduce it here.

Detail of the line recording Thomas Sweeny, which notes his parents are from the 'Green', a well known part of Dunmanway (Pat McCarthy)

Detail of the line recording Thomas Sweeny- ‘Thomas of William Sweeny Honora Sweeny…’ which also notes his parents are from the ‘Green’, a well known part of Dunmanway (Pat McCarthy)


Dunmanway Baptismal Records

Irish in the American Civil War: Generals

(1) Generals


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Categories: Cork, Generals

Author:Damian Shiels

I am an archaeologist based in Ireland, specialising in conflict archaeology.

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9 Comments on “A New Date of Birth Discovered for General Thomas Sweeny?”

  1. March 23, 2014 at 4:18 pm #

    While doing Irish genealogy I have come across this issue of an individual’s paperwork showing they were baptized before their birth date, including in my own family. After investigating, I discovered it was for religious, legal and most importantly money reasons.

    Since the church was most important in the lives of the Irish, they feared a child would not go to heaven if they died suddenly at a young age, so baptism usually happened a day or two after birth.

    The British Government required parents to register the birth of their child also within days, however to the Irish, God, the church and the child’s tiny soul trumped the British Government and the Queen. It also didn’t help that if the parents registered late, they would be fined.

    In many cases, the Irish lived on farms and away from the city center or official British government center, so many parents waited until the next time they went into town to officially register the birth of their child, telling the government official the child was a newborn, even if they were months or even a few years old.

    This confusion is common place and a person researching an Irish ancestor should always look toward the church’s baptismal records before the official government birth records.

    Three years is a long time, but its not unrealistic and using the church’s baptismal record is more accurate.

    -Jim Madden

  2. March 23, 2014 at 4:25 pm #

    Another point, naming a child after one who may have died in infancy is also not unusual to the Irish, especially if its one after the other.

    One can verify this to check the baptismal records for the official year of birth to see if there was a second Thomas listed. However, its clear these are Sweeny’s parents.

    • March 27, 2014 at 10:29 am #

      Hi Jim,

      Many thanks for the comments. I have seen that re baptism as well it certainly did occur. I agree it may be that this was an earlier child who died- I am not sure as to what appears in the register under the date that General Sweeny was thought to have been born (I imagine it was checked but am not sure), but the answer might lie there one way or the other. Either way a nice little local Dunmanway connection to still have for one of their most famous emigrants!

      Kind Regards,


  3. March 23, 2014 at 5:10 pm #

    Interesting that he was at Shiloh. My Irish born Great great grandfather, Michael William Shanahan was there as well serving the CSA with the 9th MS Infantry.

    • March 27, 2014 at 10:26 am #

      Thanks for the comment! Do you know where Michael was from in Ireland? I would love to hear more about him!

      Kind Regards,


  4. March 25, 2014 at 1:41 pm #

    I have traced my paternal line back to County Antrim and have become stuck (but am not giving up!). But their Virginia descendants served in the Civil War!

    • March 27, 2014 at 10:23 am #

      Hi Linda,

      Many thanks for the comment- it can be hard to find records here alright, worth persevering though! When did your Antrim ancestors emigrate?

      Kind Regards,


      • March 27, 2014 at 12:56 pm #

        As near as I can tell my John ARTHUR (now if that’s not a common name!) was born in Cullybacky, Antrim, Ireland in or about 1709 and he was married in Bedford County, VA in 1726. So sometime in between (I’m guessing in the 1720s because I have an unconfirmed date of his father’s death in Ireland in 1725).

      • March 28, 2014 at 9:46 am #

        Hi Linda,

        That is amazing you can get that far back- I am jealous! The majority of emigrants in that period were from Ulster, with many going South as I am sure you know. Really interesting history!

        Kind Regards,


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