At last, on the night of April 23, the gunboats "Pinola" and "Itasca" ran in and opened a gap in the boom. At 2:00 a.m. on April 24, the fleet weighed anchor, Farragut in the corvette "Hartford" leading. After a severe conflict at close quarters with the forts and ironclads and fire rafts of the defense, almost all the Union fleet (except the mortar boats) forced its way past. The ships soon steamed upriver past the Chalmette batteries, the final significant Confederate defensive works protecting New Orleans from a sea-based attack.