"Whistling Dick." This Confederate cannon which guarded Vicksburg gained widespread fame among Union soldiers and sailors because of the peculiar whistle of its projectiles.
From Photographic History of the Civil War.

The Siege of Vicksburg (continued)

THE ASSAULT OF MAY 19. By midday of May 19, Grant had completed his investment of the city. In the north, Sherman's Corps was in position opposite the Confederate left from the river (at the present location of the national cemetery) to the Graveyard Road, at an average distance of about 500 yards. McPherson's Corps took position on Sherman's left from the Graveyard Road to near the Baldwin's Ferry Road; the front of McClernand's Corps extended from the Baldwin's Ferry Road southward.

Considerable skirmishing had preceded the Union approach, as the Confederate pickets fell slowly back inside the defenses, thus preventing a close inspection of the Confederate fortifications. Grant determined, however, to attack immediately, before Pemberton had time to post his defenses strongly. The Union general ordered an assault at 2 p. m. on the 19th. Sherman's troops, whose early arrival had enabled them better to prepare for attack, moved under heavy fire against the Confederate left. Although they succeeded in making a close lodgment against the walls of the Stockade Redan, they failed to breach the works and were repulsed. McPherson and McClernand, not yet in good position for attack, were unable to do more than advance several hundred yards closer to the siege line. Grant lost 1,000 men testing the Vicksburg defenses and discovered an unyielding army manning the works. Confederate losses were slight.