It is great to have a castle, or large fortress, to set a scene in a historical novel.  The high curtain walls, the gatehouses, the murder holes and cunningly placed arrow slits.  All give the writer great scope in describing formidable bastions that appear all but impossible to penetrate.  However, history teaches us that the appearance of impregnability can be illusory, as ever since people started building walls to protect their buildings, others have been devising ways to get in – by fair means or foul. Ancient siege weapons – the Greek Catapult. When I started writing my first novel on Alexander the Great, I spent plenty of time researching the early catapults that Alexander used in besieging the many cities of Persia, in his conquest of the Persian Empire.  I proudly presented a long chapter to my father (who was helping me edit the novel) which held long explanations of the mechanics of the engines, describing them in great detail.  My father promptly put great red crosses through all the pages and scribbled “Too …