March 1, 1863 is clear as a bell, but this is the date he was last paid, his service records do not indicate his death date.

Please note the date of this letter and see my post from last month.

http://history-sites.com/cgi-bin/bbs53x/mscwmb/webbbs_config.pl?read=18552

Jackson Miss May the 10th 1863
Dear father I will write you a fee [few] lines to let you no how I am. I am verry porley. I feel some better to day though it is all I can do to set up to write. I have got to the hospittel hear at Jackson. it is a mity nice place and I have mity good attention paid to me. I want you to come and see me if you can. I think if you was hear you could get me home and if you could not you could stay a week with me you could fetch some meet___lived and stay a week or two and not cost you any thing at all. if you do come when you get to the depo go write strait up to the State house and then turn write north and inquire for the blind Asilome. it is near leg a half write north of the State house. come if you can and come as soon as you can
W.C. Grizzel
E.S. Grizzel

Source:
http://www.rootsweb.ancestry.com/~mscalhou/GrizzelCivilWar.html