The Battle of Dybbøl (Danish: Slaget ved Dybbøl; German: Erstürmung der Düppeler Schanzen) was the key battle of the Second Schleswig War and occurred on the morning of 18 April 1864 following a siege starting on 7 April. Denmark suffered a severe defeat against Prussia,[2][3] which decided the war. Dybbøl was also a battlefield in the First Schleswig War.