Probably written at the beginning of the Christian Roman Empire, in the late 4th or early 5th century AD, Vegetius's treatise is important because it gives details of training, weapons and operations as used by the roman army. It is especially important for its description of siege machines. It was seriously respected as a handbook on military science through the 15th century, and military leaders were still consulting it in the 18th century. This 11th-century copy from England is one of many surviving from countries all over Europe. Following a list of chapter titles, Vegetius begins his book with a dedication to the emperor, referring to an ancient tradition of such books written for rulers. In the left margin, a few notes left by a studious reader are visible. The chapter titles indicate the text covers such matters as training recruits, arrows, arms, munitions, and fortifications.