The interpretive sign is somewhat misleading. Frank Armstrong did not complete his mission, in fact he abandoned it two days into the campaign.
He had been ordered by Maj. Gen. Sterling Price to take his cavalry and ride the circuit around Corinth and report on existing fortifications and numbers of troops in the vicinity. He rode northwest out of Saltillo, MS and when he arrived at Holly Springs he had a fateful meeting with Brig. Gen. John Villipigue who told him the Federals were abandoning West Tennessee and it was ripe for a raid against the remaining Union troops in Bolivar and Jackson, TN.
The raid was a failure, for not only did he not complete the original mission, he was turned away from Bolivar, was bested by a mere 250 men at Medon and beaten at Britton Lane. Price later reported Armstrong lost only 115 men during the raid, a number that is actually about 1/3 of the true number that was between 300-400.
Had Armstrong ridden around Corinth as instructed he may have returned with information which would have been invaluable for Van Dorn's attack on Corinth a month later.
I wrote a feature length article on this raid for Blue and Gray Magazine but, sadly, it went out of publication before we could get it to print.
All the best,
Tom