Which tone is created by words, such as “maniacal,” “furious,” and “quivering,” in lines 55–59?

All of these wonderful words convey a growing sense of chaos as the company of soldiers finds itself under attack. The lieutenant has just been shot, and the men in his company are frantically trying to get a handle on the situation. No one yet knows for sure where the shot came from, and this adds to the sense of panic rapidly building within the ranks.
To make matters worse, the maniacal horses are getting pretty skittish. As the buglers and orderlies desperately try to maintain their positions in the face of booming shells, their steeds are going crazy, making furious quivering leaps amidst the enveloping chaos. Although Crane uses these epithets to describe the horses, he could just as easily be talking about the soldiers, because they too are in complete panic over this sudden and unexpected assault.