A kind of flags have been designed for naval battles at some stage in the Civil War; these blanketed distinguishing marks for ships

https://johnathanxqgy357.inkharbory.com/posts/the-history-behind-the-civil-war-flag-symbols-of-a-nation-divided

A sort of flags had been designed for naval battles in the time of the Civil War; those covered distinguishing marks for ships engaged in battle on rivers and seas alike.