On the night of April 22, 1862, a federal steamboat went right up to the chain rigged between the different sunken wrecks. Even as the two forts commenced firing, an intrepid Yankee got off his boat and onto one of the hulks, where he unwrapped the chain, allowing his steamboat through. The vessel came through, went upstream a few hundred yards, then turned, and—with the current of five knots behind it—rammed the chain, breaking it. The way had been cleared.
Union ships surround New Orleans in 1862 in this illustration from the 1894 book Campfires and Battlefields.