This post ia based on, and provides additional materials for, my book, King Alfred: A Man on the Move, available through Amazon and bookshops.
This matter turned out to be more complicated than I had anticipated. It will therefore be broken down into a few posts. This one is more-or-less introductory, to be followed by posts on Hertford and Ware.
The Anglo-Saxon Chronicles tell us that in 895 some Vikings left Mersea Island in Essex and built a fortress by the River Lea at a point about 20 miles north of London. They were then attacked by garrisons loyal to Alfred, which were in turn beaten back by the Vikings, with some loss of life. We are then told that later that year, at harvest-time, King Alfred himself arrived and camped in the vicinity of the Viking fortification in order to prevent the Vikings from stopping the locals from reaping their corn. The Anglo-Saxon Chronicles also tell us that after this, but still in the same year, Alfred rode up the River Lea to see where the river could be obstructed in order to block the Viking ships in. The Anglo-Saxon Chronicles record that the river was indeed obstructed and that Alfred started to build a fortification on either side of the river. The Vikings abandoned their ships because they realised that they were being trapped, and fled overland all the way to Bridgnorth (or possibly nearby Quatford) on the River Severn in what is now Shropshire. We do not know whether the ships were being physically hemmed in or whether they were being immobilised because of some sort of drainage of the river.
It is worth noting that the Annals of St Bertin inform us that in 862 Charles the Bald, King of West Francia, had hemmed the Vikings in on the River Marne by re-building a destroyed bridge and placing troops on both banks. Trapping the Vikings upstream was a tactic that had been used before.
The River Lee Navigation (the river is variably called “River Lea” or “River Lee”, whereas the man-made navigation is always called “Lee”), which runs the whole stretch of our area of interest from Hertford, in Hertfordshire, to London, was cut in 1770. However, before 1770 there were at least four streams, and there may have been as many as seven, so it seems difficult to establish with certainty the course of the River Lea in Alfred’s time. Back then, if the total volume of water was anything like it is today, feeding through different streams and large lakes, the river must have been much wider than the remnants of what today are said to be original course of the Lea.
So, we have four things that it would be nice to locate. The Viking fortification, Alfred’s camp, the point where the river had been obstructed, and Alfred’s pair of incomplete fortifications on the River Lea. Because we cannot be certain about the distance represented by a mile (with Saxon, Roman and modern miles being slightly different) , or how accurate measurement was at the time, I feel that it would be sensible to consider the distance for the Viking fortress of twenty miles north of London as approximate. Twenty miles takes us to somewhere just south of Hertford, and perhaps the stretch of the river near Hoddesdon and Broxbourne. Only slightly upstream on the River Lea are the towns of Hertford and Ware, and I think these deserve serious consideration because they are approximately twenty miles from London. I shall look at these places more closely in later posts.