P 80
The Arkansas troops in the western division of General N.B. Pearce had not yet been sworn into state service. For this the Military Board sent Dandridge McRae, the Inspector General, to Pearce’s headquarters on June 21 with instructions to swear all the men of his command into the service of the state with the right of transfer to Confederate service. Pearce refused to allow the men to be sworn, and Hardee advised the Military Board that he would not receive Pearce’s troops until after the pending battle at Springfield, Missouri was fought.
According to this it was sometime before 21 June 1861.