John D. Billings, Hardtack and Coffee: The Unwritten Story of Army Life

[59] Then the main lines, both infantry and artillery, thinking it might possibly be a night attack, would join in the fire, while the familiar Rebel yell, responded to by the Union cheer, would swell louder as the din and roar increased. But soon the yelling, the cheering, the artillery, the musketry would subside, and the mortar batteries with which each fort was supplied would continue the contest, and the sky would become brilliant with the fiery arches of these lofty-soaring and more dignified projectiles. As the mortar-shells described their majestic curves across the heavens every other sound was hushed, and the two armies seemed to stand in mute and mutual admiration of these magnificent messengers of destruction and woe.

Sometimes a single shell could be seen climbing the sky from a Rebel mortar, but ere it had reached its destination as many as half a dozen from Union mortars would appear as if chasing each other through the air, anxious to be foremost