One of the most successful allies in the defense against the christian/frankish invasion, for the danish (jutish) vikings, was Nature! The fact that most of the Jutland Penisular was riddled with dangerous swamps, made passing of the cavallery, the franks relied on, impossible! The Norsemen however, were very familiar with fighting in such a terrain! IT IS IMPORTANT TO KNOW THAT THE WAR BETWEEN THE CHRISTIAN COUNTRIES, AND THE VIKINGS, WAS STARTED BY THE CHRISTIAN ANTI-PAGAN CAMPAIGN!!!