Rosemary Sutcliff's The Eagle of the Ninth is the classic story of a young Roman centurion sent out to recover the infamous Ninth Legion's missing symbol of honor. It is also Book One in The Roman Britain Trilogy.
The Ninth Legion marched into the mists of Northern Britain--and they were never seen again. Four thousand men disappeared and their eagle standard was lost. It's a mystery that's never been solved, until now . . .
Marcus Aquila has to find out what happened to his father, who led the Ninth Legion. So he sets out into the unknown, on a quest so dangerous that nobody expects him to return.
Great middle grade novel to add onto a Waldorf class 6 Roman unit of study or to Class 7 or Class 8 as an extender to what they learned in Class 6. Not really appropriate for Waldorf Class 5 Roman Unit, but reading level is rated for their age-range.