Trans-Missippippi is a region of Missouri, Arkansas, Texas, Indian Territory (now Oklahoma), and Louisiana west of the Mississippi River).
Reverse colors of the confederate battle flag were used by many Confederate units during the Civil War, typically in more western areas. The Confederate Army's Trans-Mississippi Department included the region of Missouri, Arkansas, Texas, Indian Territory (now Oklahoma), and Louisiana west of the Mississippi River). The flags of the Trans-Mississippi had reversed coloration (blue field with red bars). This type of flag is often called the Taylor Battle Flag after General Richard Taylor, whose army employed it in West Louisiana from 1864 to the end of the war. (Taylor was the son of Mexican War hero and US President Zachary Taylor.) There are two surviving examples of this flag used in Tayor's army.
Several varieties with the reversed colors existed. One was that of the 3rd Texas Infantry. This flag was made in Cuba, paid for by Confederate expatriates living there who donated it to the regiment. The stars and unit designation were embroidered in silver wire and the fringe was knotted silk.
Reversed colors were not totally limited to the West; we have a surviving example of one sewn for by the ladies of Asheville for the 39th North Carolina Regiment (which saw action in Mississippi). The garrison flag of Fort Fisher (south of Wilmington, NC) was captured upon its surrender on January 15, 1865. This flag was a second national Confederate States pattern which utilizes the battle flag as it's canton (upper corner). The colors of the canton were reversed but still edged with white trim.
Used in the Canton on Sam Maxey Bell's flag and the Ft Fisher Flag.