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 seige 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. Vegetius discusses matters relevant to weapons and defense. On this page, defensive walls and siege machines are expounded. In this section, Vegetius gives details of a seige machine called an onager. Production of the book has begun to lapse by this point in the text. In the left margin, a section title had to be written in because it was left out of the usual position in the text. Also, the blank space at the edge of the block of text was intended for a large letter P. As it is, the first line of the section is incomplete.