Fort Jefferson never was used for it’s original purpose to defend the waterways in the Gulf. It was never fully functional and was never completed. After the new artillery was brought over from Europe that made brick walls obsolete the fort was abandoned by the army and much of the arms were sold for scrap except the largest cannons that still sit on the top which were too difficult to move. Later it became possibly a turning point in the civil war. The story went that the Confederate navy went to occupy it but the Union Navy got there first. Little did the Florida naval vessel know that this fort was never completed. So when the Union threatened to open fire they retreated. It was later used to fuel ships in the war with much need coal. It later became a infamous prison that housed Dr Mudd.