Jutland ( /ˈdʒʌtlənd/; Danish: Jylland [ˈjyl.anˁ]; German: Jütland), historically also called Cimbria, is the name of the peninsula that juts out in Northern Europe toward the rest of Scandinavia, forming the mainland part of Denmark. It has the North Sea to its west, Kattegat and Skagerrak to its north, the Baltic Sea to its east, and the Danish–German border to its south. The German state of Schleswig-Holstein is part of the Cimbrian Peninsula but not part of Jutland.

Today, the Danish parts of Jutland belong to either of the three administrative regions North Jutland, Central Jutland or Region of Southern Denmark. The German parts of Jutland peninsula today form the state of Schleswig-Holstein and the city of Hamburg.

Its terrain is relatively flat, with heaths, plains and peat bogs in the west and a more elevated and slightly hilly terrain in the eastern side. The Danish portion has an area of 29,775 km² (11,496 sq mi) and a population of 2,528,129 (2008). Population density is 84 per km² (218 per sq.mi.).

World War I (WWI), which was predominantly called the World War or the Great War from its occurrence until 1939 (World War II), and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. It involved all the world's great powers, which were assembled in two opposing alliances: the Allies (based on the Triple Entente of the United Kingdom, France and Russia) and the Central Powers (originally centred around the Triple Alliance of Germany, Austria-Hungary and Italy; but, as Austria–Hungary had taken the offensive against the agreement, Italy did not enter into the war). These alliances both reorganised (Italy fought for the Allies), and expanded as more nations entered the war. Ultimately more than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history. More than 9 million combatants were killed, largely because of enormous increases in lethality of weapons, thanks to new technology, without corresponding improvements in protection or mobility. It was the sixth-deadliest conflict in world history, subsequently paving the way for various political changes such as revolutions in the nations involved.