You're probably correct, Bubba. I have no ox in this argument, but some newspapers of the time spelled the name Quantrell. See: New York Times and Richmond Dispatch. My hard copy of Frank Leslie's Illustrated Newspaper spelled it Quantrell also. The Official Records, on the other hand, spelled it Quantrill.
Newspapers are not necessarily great arbiters of spelling. The NYT, for example, consistently spelled Fort Sumter as Fort Sumpter.
The Richmond article mentions something I'd never heard before, that Quantrell/Quantrill was a Jayhawker for a year.
There's a good discussion of the Quantrill vs. Quantrell controversy here (hardly an anti-Quantrill site, by the way). The short version is that a young lady named Annie Fickle made them a flag and mispelled the name on it, but out of respect and appreciation to her generosity, they didn't correct it.
The Richmond article mentions something I'd never heard before, that Quantrell/Quantrill was a Jayhawker for a year.
Yeah, you might want to take that with a grain of salt. The story about heading out to California and his brother getting killed was a fabrication by Quantrill, who insisted that all his men had to have a personal revenge motive to ride with him, but it's all Quantrill trying to create his legend. The truth is that of Quantrill's three siblings who lived to adulthood, none were killed in Kansas. According to an 1888 article in the Louisville Courier-Journal (quoted in Quantrill and the Border Wars (1909) pg. 29, Quantrilll's mother showed off the family bible and said:
"We had eight children in all, but four of them died in their infancy. Here, in the old Bible in which the records were kept, you see the names and dates. The records were all made by my husband, and I have never written a lline in the old Bible since his death, which accounts for the balance not being in. Only one of my children is still alive. Thomson lives in Montana, where he has a family and is doing well. My daughter Mary died in 1863. She was never married. My son Franklin died six years ago, leaving his wife and four daughters, two of whom are now grown. One is a teacher at Canal Dover."