The Vallum was a form of Ancient Roman Military Field Engineering, most seen in the 2nd and 3rd Century AD. It was further most commonly seen in Roman Colonies or during Roam expansion into potential Territories. Although Roman by design, The Vallum style of fortification may have been borrowed by several similar field engineering models of Ancient Greece. In The Roman attempts, The Vallum was by nature – a simple ditch. Dug only several feet deep, the earth from this trench would be thrown onto the above ground and used as an earthen berm or embankment. This process was continued onward I the direction needed. The Vallum could be a series of non-connected trenches (squared) or a complete circular pattern. In a circular pattern, The Vallum would encircle a Roman Camp (Legion). Slaves were not used and The Vallum's construction was by it's Soldiers. In cases of a more permanent ''Base Camp'' (long term), Vallum's were equipped with a further protective device known as a ''Vallum Spike''. Unlike the previously discussed Sudis – or Camp Spike. The Vallum Spike was seen as a more permanent defensive/offensive device. Whereas The Sudis was a single sharpened wooden spike, driven into the ground to impede Enemy movement during any attack, The Vallum Spike was a form of Cheval de Frise (seen in use centuries later). The Vallum Spike was a cross shaped device made of wood. Joined in the center (and looking very much as a wheel spoke), it was placed inside (anchored) of the earthen berm. The far rear and bottom extension served to hold the Spike in the ground. The farthest and top spike were exposed from the earth. An advancing Enemy could be impaled this from two points. Often, Vallum's would be used to mark boundaries after their use as a fortification was ended. In this usage, The Vallum Spike was removed and stone was placed in it's stead. Often, these wall replacements were only 3 to 5 feet in height. Such boundaries markers would often be patrolled by Colonial or Auxiliary Units. Built to last, some examples of The Vallum fortification can still be seen today. One of the best known is Northern England's Hadrian Wall, which dates from the 1st Century AD.