books.google.co.uk - Warfare in Europe in the middle ages underwent a marked change of emphasis as urban life expanded. The concentration of wealth represented by a city was a valuable objective, and the static nature of a siege was infinitely preferable to the uncertainties of campaign. As the incidence of sieges increased,...http://books.google.co.uk/books/about/The_Medieval_City_Under_Siege.html?id=OJIFpd09vCgC&q=crossbow&utm_source=gb-gplus-shareThe Medieval City Under Siege
