I came across this text as part of my research for a recent university assignment, I've now completed the essay and handed it in but I'm left wondering what this 'veto' is? and how it was used. Here's a link to the full text:
Vegetius was a late Roman military writer (4th/5th century), author of the Epitoma rei militaris (also sometimes known as De re militari). This military compendium was the most popular military manual of the Middle Ages, surviving in c. 300 manuscripts. It was translated early into the vernacular and remained influential well into the early modern period.
Vegetius advocates a cautious approach to engaging in battle, because no matter how well prepared a general and army might be, the outcome is always uncertain.
Some military historians have tried to link Vegetius' caution to the limited gains and limited nature of medieval warfare: medieval warfare was not total war in the modern sense.
Medieval military historians did have something of a debate relatively recently about whether medieval warfare really was 'Vegetian' in the Journal of Medieval Military History. See links below.
The standard edition of Vegetius in Latin is: Reeve, Michael D. (ed.). Epitoma rei militaris. Oxford Medieval Texts. Oxford, 2004.
It is also available in multiple English translations, such as: Milner, N.P. (tr.). Vegetius: Epitome of Military Science. Liverpool, 1993.
For the origins of the debate in the Journal of Medieval Military History, see:
--Rogers, Clifford J. (2003). "The Vegetian 'Science of Warfare' in the Middle Ages". Journal of Medieval Military History. 1: 1–19.