Greyhound is based on true happenings. It gives a fictionalized account of real historical occurrences related to naval warfare during that time period. While it may not be a 100% accurate retelling, it captures the essence of the events.
It is. The movie takes elements from actual naval battles and incorporates them into the storyline. However, some artistic liberties might have been taken for dramatic effect.
In reality, 'The Greyhound' is a work of fiction. The plot and characters are created by the author's imagination, but there could be elements that resemble real-world scenarios in a general way.