John IV, Duke of Saxe-Lauenburg German duke (1350–1414) Parents Eric IV, Duke of Saxe-Lauenburg Sophia of Braunschweig-Lüneburg Children Siblings Magnus of Saxony-Lauenburg Catherine of Saxe-Lauenburg, Duchess of Mecklenburg Eric V, Duke of Saxe-Lauenburg Bernard II, Duke of Saxe-Lauenburg Sophie of Saxe-Lauenburg Agnes of Saxe-Lauenburg Albrecht von Sachsen-Lauenburg Agnes of Saxe-Lauenburg