Circuses were in need of music that would stir the audience into a frenzy, as four-footed animals galloped across the ring.
Although screamers tend to follow the march form, they are often abbreviated, and additions, such as a quick cornet call introduction to a new melody, are included.
Screamers are a very demanding type of music, due to their extremely fast and advanced rhythms, especially the low-brass parts.
The low-brass section can be playing a long, stately melody, while the woodwinds can be moving along with a phrase of 16th notes, or vice versa.
John Philip Sousa wrote "On Parade" and a few others, but his writing in the circus march style is not highly regarded.