Duke Eric III of Schleswig was a nobleman who ruled in the late 14th century. He was part of the House of Schauenburg and held the title of Duke of Schleswig from 1359 until his death in 1412. His reign was marked by efforts to strengthen his territory and maintain peace in the region. Eric III was known for his involvement in various political alliances and conflicts, which were common during his time. He played a significant role in the power dynamics of Northern Europe, particularly in relation to the Danish crown and neighboring territories. His legacy is tied to the complex history of the Duchy of Schleswig.