My ancestor was in the First Wisconsin. In regards to diary accounts of the battle on April 26th, 1863 near Cape Girardeau, MO. The North Dakota State University has a transcribed Diary that they will copy and forward for only $5. It is from Lt. Oscar Barrett of Company D and pretty much covers 1863. I think you can get 1864 and 1865 for $5 more.

Anyway, for April 26th, 1863 his entry is as follows:

"We saddle up at 2pm and form line of battle. Marmaduke (Rebel General)gives us till 11 AM to surrender. They drove in our pickets (guards) on the Jackson Road at 1/2? The first gun was fired from fort at ten minutes before 11 AM Fort was engaged. Firing ceased at 1 PM. Rebels retreated. We lost 6 men."

Hope this of help. The regiment later (May, 1865) chased Confederate President Jefferson Davis through Georgia. About 75 men of the regiment recieved one to two year's pay as part of the reward. A detailed account of the pursuit is available on line.

I hope this was of help!