May 2 1862, Wrote Gen. McClernand, “A note just received from General Halleck says that the enemy are moving toward Purdy, to operate on our flank. Have all the approaches by way of Owl Creek well watched, and tomorrow early, or to-night if practicable, a strong reconnoitering party toward Purdy. Cavalry alone will answer for this reconnaissance. I will direct General Wallace to use extra vigilance on the two roads leading from here. ”

The Papers of Ulysses S Grant, Vol 5, p 108

O.R., I, x, part 2, 157