"Gallop" originated from the Middle English galopen (circa 1400), borrowed from Old French/Anglo Norman galoper.   "Gallop" is a doublet of wallop (Middle English walopen), meaning they share the same origin, with wallop coming from the North French form waloper.   It describes a horse's fastest gait, likely referencing a "good" or rapid, efficient run. 

According to the Oxford Endlish Dictionary (OED), the verb gallop first appeared in English in the early 1500s (around 1515).  The earliest evidence is found in a translation by John Bourchier, 2nd Baron Berners.  The noun gallop also has its earliest known use listed in the early 1500s.  While the OED notes the early 16th century for the noun, other dictionaries cite similar late Middle English origins, with some sources mentioning usage from the early 15th century (c. 1400–1425). 

"Galloping" in storytelling refers to a fast-paced, high-momentum narrative tempo used to accelerate through action, suspense, or plot-heavy scenes, ensuring the story moves forward without stalling. It is essential for creating urgency and excitement, forcing the reader to turn pages quickly, which is crucial for genres like thrillers, action-adventure, and high-intensity fantasy.