Final answer:
The sentence is looking for a word that describes the intense feelings a person would have in response to cannon fire, with suggested words being 'fear' or 'shock'.
Step-by-step explanation:
The suitable word to complete the sentence and convey the intense emotions the speaker felt when the cannon was fired. One might choose words such as fear, shock, disbelief, or horror, depending on the exact nuance they want to express. These examples align well with the vivid descriptions from provided excerpts, where characters experience extreme emotions in response to violence, war, or discovery.
For instance, characters endure chaotic environments where cannons roar and grapeshot shatters the forest canopy, or they experience profound transformations that quiver with the pulse of newfound knowledge. In all these scenarios, potent feelings overwhelm the senses, akin to the speaker's reaction to the unexpected cannon fire.