Okay in mid 1861 Hardee commanded all
Confederate troops in Northern Arkansas. He invaded Southeast Missouri on July 31st this was in conjunction with Pillows Confederate Army of Liberation invading Missouri at New Madrid and linking up with M. Jeff Thompsons Missouri State Guard Troops.
The idea was to gain control of the Missississippi and make Cairo Illinois untenable for Union forces and thereby protect and secure the Tennessee and Cumberland rivers for the
CS, and eventually link up with Prices State Guard and secure Missouri. Hardees presence in SE Mo factored into Lyons defeat at Wilson's Creek because with Pillow and Hardee in Southeast MO Fremont withheld reinforcements from the Union forces in SW Mo.
Eventually however Grant did secure the Mississippi and rendered the SE Mo incursion mote.
Could be that Davis felt that Hardee and Pillow were to blame for the loss of the Mississippi and this is the reason he never was granted larger command. Coupled with Hardees berating of Jeff's fairhaired boy Braxton.