The Federal mortar-fleet was getting ready for action. Topmasts were lowered, all spars and booms unshipped, the main-decks cleared, and armour of chain cables was improvised to protect the gunners. The ships were painted with mud to make them invisible. On the 17th of April the order was given to advance up-stream. There was a thick forest on the western bank, a low bank and marshy ground on the east. In order to confuse the enemy, the masts and rigging of the Northerners were festooned with leafy branches; others were sheathed with reeds to blend with the background of the river-bank. Five sloops of war waited behind the mortar-boats, carrying 104 guns; 150 boats supplied with grapnel-ropes, axes, and buckets, were ready to deal with the fire-ships. And they soon had the work to do, for one dark night a blazing raft came down upon them, lighting up water and bank, trees and rushes; but the _Westfield_ dashed into the burning pile and turned her hose upon it; and the boats leapt forth to hack and grapple and plunge the burning timbers into the river. Then cheers broke forth when the peril had been subdued. At 9 a.m. of the 16th of April Fort Jackson threw a shell into the Northern flotilla a mile off, and at once the mortar-boats replied, sending their big shells with great accuracy into the very ramparts. New Orleans, seventy-two miles away, distinctly heard the thunder of the bombardment, kept up for more than a week. The citadel was set on fire, the walls cracked and shattered, and the forts were flooded. The men on deck would fall down and sleep in the midst of the great thunder, so exhausted were they by toil night and day. On the second day the _Carleton_ received a shell into her magazine, which exploded, and she sank. At the end of a week, after all this terrible storm of flying metal, only one man had been killed and six wounded in the Federal fleet. But the forts had not been silenced. On the 24th of April, at 2 a.m., two red lights were run up on the flag-ship, and very soon the fleet was under way for the passage between the forts. As each ship passed it delivered its broadside and swept on towards the gunboats beyond. Fire-rafts kept floating down, and the roar of 500 cannon shook the air. The _Ithaca_ was riddled by shot and fell behind. The ram _Manasses_ came down on the flag-ship, and Admiral Farragut got aground while trying to avoid her. His ship took fire from a fire-raft, but it was extinguished. Captain Boggs in the _Varuna_ sunk five gunboats one after another, then his vessel’s sides were stove in by a ram; but with his last broadside before he sank he disabled her. A boy named Oscar was on board the _Varuna_, only thirteen years old, and during the fight was very busy passing ammunition to the gunners. All covered with dirt and powder-begrimed, he was met by Captain Boggs, who asked where he was running in such a hurry. “To get a passing-box, sir. My other was smashed by a ball.”