Unless he was wounded somewhere else and was then evacuated to Fort Thompson, the notation seems to be in error. The first recorded skirmish in the vicinity of Fort Thompson occurred on February 24, 1862, a brief affair between pickets. The Federal army didn't arrive in any substantial strength until February 28-March 1. The siege is reckoned to have officially begun on March 3.

The deaths (and there were many) at Fort Thompson prior to February 24, 1862, whose causes were recorded were all due to disease, mostly pulmonary disorders, such as pneumonia.