The fesse is a broad horizontal band across the centre of the shield, in very ancient times it was said to occupy one third of the area height of the shield A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P117, however it soon became somewhat narrower. This created an opportunity to add decorative edging to the band, of many forms, and to very pleasing artisitic effect, at least close up – it must be admitted that at distance some of the forms are hard to distinguish! An edge which is decorated like the top of a castle wall is said to be embattled, or sometimes crenelle, from the original French. (In castle building terminology the parts of the wall that stick up are known as merlons, and the resulting gaps as crenels). A whole sub-section of heraldic terminology has sprung up to describe whether these crennellations appear on which edges, whether they line up or alternate, have additional steps or rounded tops. The interested reader is directed to the reference for the full set! A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Embattled For obvious reasons, use of this decoration is to be associated with castles and fortified towns, an early authority, Guillim suggest also some association with fire, but with out clear reason The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P41. In all, this is one of the more common, and most effective and appropriate of the decorative edges.