As June wore on, Grant pressed the siege with vigor. Johnston tried to help Pemberton, but could not. Grant proceeded to mine under some of the Confederate works to blow them up. One of these, known as Fort Hill Bastion, was in front of McPherson, ad on the afternoon of June 25 it was exploded with terrible effect, making a great breach, at which a fierce struggle ensued.

Blowing Up Fort Hill Bastion

As June wore on, Grant pressed the siege with vigor. Johnston tried to help Pemberton, but could not.…

The torpedoes used by the Confederates were various in form and construction. The most efficient ones were the galvanic and percussion. The percussion or "sensitive" ones exploded by the act of forcible contact. Some of these were made in the form of a double cone, with percussion tubes arranged around the cylinder thus formed, at the point of contact of the bases of the cones.

Percussion Torpedo

The torpedoes used by the Confederates were various in form and construction. The most efficient ones…

The steam-vessels were protected by torpedo-nets formed of ropes weighted with iron or lead, and furnished with hooks to catch the little submarine mines. These nets were hung from spars placed athwart the bowsprit in front of the vessel, and sometimes in like manner along its sides.

Torpedo Net

The steam-vessels were protected by torpedo-nets formed of ropes weighted with iron or lead, and furnished…