There must be some mistake. Just this morning I reviewed the NYT of July 15 and they report 700 Confederates killed and the rest fleeing to Arkansas after the great Union victory at Carthage.
Historians give the win to Confederates, noting the role of Ranger Capt. Jo Shelby, the Missouri Confederate State Militia outnumbering the Union 2nd Brigade at least four-to-one.
It seems Union forces fought well, but at the end of the day, outnumbered were ordered to retreat.