I labored to prepare you a document of a timeline regarding the dismounting of cavalry in Van Dorn's army. I included references to many, if not all, units that were do selected.
Unfortunately, while trying [and failing] to insert an image of the actual order I lost the word document. My inadequate computer skills have thus far failed me in posting an image of Special Order #43 dated 4/8/62, Des Arc, Ark. Nor have I been able to retrieve the untitled and unsaved word document.
The order, in so may words, instructs all 12 months cavalry, will be immediately dismounted. Reasons given were: impossible to furnish sufficient forage for so large a cavalry force; and insufficient transportation [boats] to transfer the army to Memphis.
I hope this will suffice.