The iron helmet dates from the time of the Burgundian siege of Neuss. In shape it is what is known as a Burgundian sallet with a hinged visor and a very narrow eye-slit. The helmet was found during earth-moving operations outside the gates of the city along with many other weapons and pieces of military equipment from the time of the Cologne War. The siege in the years 1474 and 1475 is considered a turning pointin Neuss history. After the Cologne archbishop Ruprecht of the Palatinate was dismissed by the cathedral chapter in a dispute over tax revenues, he appealed to his relative, the Duke of Burgundy for help. On July 29, 1474, Charles the Bold reached Neuss, which he besieged for ten months and attacked by some of the most modern artillery of the time. Only the arrival of a relief army under Emperor Frederick III ended the siege on 29 May 1475. As a reward for their successful resistance the emperor grants privileges to the city of Neuss, but it took a long time for Neuss to recover from the destruction caused by the siege.