1917 was a pivotal year for both sides in the conduct of the First World War. Decisions made during that year were to have a profound impact on what happened the following year and the eventual outcome of the war. One of those events provides the backdrop for the incredibly successful movie by Sam Mendes, "1917". "1917" was a huge blockbuster success and was inspired by the director's great-grandfather. So how much was fiction and how much was fact? This documentary analyses the movie and looks at what elements are true and why 1917 was such a momentous year in World War II history.