Sorry, didn't mean to include that photograph. Just the link to the Wikipedia Article on the Arkansas Militia in the Civil War.

I would also recommend [Pillars of Power: Steps Toward Secession by Jim Lair (Tate Publishing, 2009). Softcover, 2 maps, illustrations, appendices, notes, bibliography. Pages main/total:389/514. ISBN:978-1-60696-381-4 $29.99]. Lair's book has a rather long discussion of secession and slavery at the beginning, but then moves on to a pretty good summary of the state's preparations for war.

There is also an often quoted AHQ article on the State Military Board which would probably be helpful. Huff, Leo E., "The Military Board in Confederate Arkansas", Arkansas Historical Quarterly, XXVI (Spring 1967)