I know I've seen it too; but where? I believe Chubb was the harbormaster of Galveston, TX who wrote a nasty reply to a Federal ship that was trying to land at Galveston early in the war. It made big headlines at the time. Joshes may refer to the number of Scots-Irish in Arkansas, and don't forget the "Mudheads" referring to the North Carolina regiments attached to McNair/Reynolds. (Maybe it's in Reynolds Diary)!
All are terms of affections, such as before an attack, "Well, Mudheads. You goin'?" / "We'll go if'n you do, Josh!"