Davide,

The US Army had flag pole regulations since their flags were 6 by 6 1/2 feet in size. Those poles were to be ten feet long. Their thickness was about 3 inches around.

The Confederates had no flag pole regulations that I have seen but since their flags were typically smaller the poles would be shorter - probably at least two feet longer than the flag's width. As the war went on manufactured flag poles seemed to become more scarce and tree branches were used quite often to replace them.

I think the wood used was Ash for many flag poles. Two to three inches around would be fine.

Greg Biggs