The explosion was terrific and was seen and heard for many miles up and down the river.

Had it occurred near the vessels, it would have destroyed every one of them." [Illustration: GUN AND MORTAR BOATS ON THE MISSISSIPPI.] After the fall of New Orleans Porter was sent to Ship Island to await the attack that was in contemplation upon New Orleans.

He was recalled by Admiral Farragut to aid him in the siege of Vicksburg.

In passing the batteries Porter had three of his vessels disabled and twenty-nine men killed and wounded.

The capture of that last Confederate stronghold on the Mississippi was a severe and tedious task, but General Grant, with that bulldog tenacity for which he was famous, held on until the 4th of July, 1863, when General Pemberton, the Confederate commander, surrendered his whole garrison of more than 20,000 men.