When I was a boy, Rosemary Sutcliff's 'The Eagle of the Ninth' was one of my favourite stories. That two films, one based on the events surrounding the supposed, disputed, disappearance of Legio VIIII (or IX) Hispana in Northern Britain (Centurion), and a second, following Sutcliff's story of an attempt to discover what had happened to the legion, and recover its eagle, filled me with a mixture of excitement and trepidation. Excitement, because these could be great stories, if well told, and well filmed, and trepidation from knowing how adept film-makers are at completely messing up both a good story and the history behind it!
Centurion wasn't a bad story at all, if you leave out a few minor details - like legionaries armed with spears instead of pila, and the 'great balls of fire' (with apologies to Jerry Lee Lewis). A reasonable attempt, by cinema's standards, at telling a plausible story.