ds1 is 9 and really enjoys reading about history and ancient civilisations - with a particular fascination for war and weapons he has several usborne roman type books, any ideas for anything a bit more unusual?
Rosemary Sutcliff! The Eagle of the Ninth series are all Roman, Warrior Scarlet is Bronze Age Britain, but there are zillions (historical fiction really pickled in reaslistic detail and with utterly gripping characters.)
The Michelle Paver Chronicles of Ancient Darkness series books are set in the Stone Age. They're aimed at 9-12's and 'Ghost Hunter' (the latest book) has just won the Guardian Children's Fiction Prize.