The Danevirke is a system of Danish fortifications. This important linear defensive earthwork across the neck of the Cimbrian peninsula, was initiated by the Danes in the Nordic Iron Age at some point before 500 AD. It was later expanded multiple times during Denmark's Viking Age. The Danevirke was last used for military purposes in 1864 during the Second War of Schleswig.
The Danevirke stretches for 30 km, from the former Viking trade centre of Hedeby near Schleswig on the Baltic Sea coast in the east to the extensive marshlands in the west of the peninsula. Another wall named Østvolden, between the Schlei and Eckernförde inlets, defended the Schwansen peninsula.
According to written sources, work on the Danevirke was started by the Danish King Gudfred in 808. Fearing an invasion by the Franks, who had conquered heathen Frisia over the previous 100 years and Old Saxony in 772 to 804, Godfred began work on an enormous structure to defend his realm, separating the Jutland peninsula from the northern extent of the Frankish empire. The Danes however, were also in conflict with the Saxons south of Hedeby during the Nordic Iron Age and recent archaeological excavations have revealed that the Danevirke was initiated much earlier than King Gudfred's reign, around 500 AD and probably well before that even.
With the emergence of national states in Europe during the 1800s, the Danevirke became a powerful symbol for Denmark and for the idea of a unique Danish people and Danish culture. Throughout the nineteenth century, Denmark and Germany struggled politically and militarily for possession of the territory variously known as Sønderjylland or Slesvig by the Danes and Schleswig by the Germans. Two wars were fought, the First Schleswig War (1848-1851) and the Second Schleswig War (1864), eventually resulting in a Danish defeat and subsequent German annexation. In this hostile context, the Danevirke played an important role, at first as a mental cultural barrier against Germany, but soon also as a concrete military fortification, when it was strengthened with cannon emplacements and entrenchments in 1850 and again in 1861.
Archaeological excavations in 1969–75 established, with the help of dendrochronology, that the main structure of the Danevirke had been built in three phases between AD 737 and 968. It is, therefore, contemporary with Offa's Dyke, another great defensive structure of the late 8th century.
Recent investigations suggest that the Danevirke was not only, and not even primarily, built for military purposes. The archaeologist Henning Hellmuth Andersen found that in an early stage the main 'wall' consisted of a ditch between two low embankments. The historian argued that the Kograben south of the main wall consists of an embankment accompanied by a ditch on its northern side, which would have been counterproductive for a Danish fortification. Rather, the main construction, in its earliest stage, and the Kograben would have been shipping canals. The existence of a shortcut for shipping between the Baltic and the North Sea via the Schlei in the east and the rivers Treene and Eider in the west had long been recognized, but historians had previously believed that boats had been moved between the Schlei and Treene by portage on rollers.References:
From its origin as a small stronghold built by the ancient Illyrian tribe Dalmatae, becoming a royal castle that was the seat of many Croatian kings, to its final development as a large fortress during the Ottoman wars in Europe, Klis Fortress has guarded the frontier, being lost and re-conquered several times. Due to its location on a pass that separates the mountains Mosor and Kozjak, the fortress served as a major source of defense in Dalmatia, especially against the Ottoman advance, and has been a key crossroad between the Mediterranean belt and the Balkan rear.
Since Duke Mislav of the Duchy of Croatia made Klis Fortress the seat of his throne in the middle of the 9th century, the fortress served as the seat of many Croatia"s rulers. The reign of his successor, Duke Trpimir I, the founder of the Croatian royal House of Trpimirović, is significant for spreading Christianity in the Duchy of Croatia. He largely expanded the Klis Fortress, and in Rižinice, in the valley under the fortress, he built a church and the first Benedictine monastery in Croatia. During the reign of the first Croatian king, Tomislav, Klis and Biograd na Moru were his chief residences.
In March 1242 at Klis Fortress, Tatars who were a constituent segment of the Mongol army under the leadership of Kadan suffered a major defeat while in pursuit of the Hungarian army led by King Béla IV. After their defeat by Croatian forces, the Mongols retreated, and Béla IV rewarded many Croatian towns and nobles with 'substantial riches'. During the Late Middle Ages, the fortress was governed by Croatian nobility, amongst whom Paul I Šubić of Bribir was the most significant. During his reign, the House of Šubić controlled most of modern-day Croatia and Bosnia. Excluding the brief possession by the forces of Bosnian King, Tvrtko I, the fortress remained in Hungaro-Croatian hands for the next several hundred years, until the 16th century.
Klis Fortress is probably best known for its defense against the Ottoman invasion of Europe in the early 16th century. Croatian captain Petar Kružić led the defense of the fortress against a Turkish invasion and siege that lasted for more than two and a half decades. During this defense, as Kružić and his soldiers fought without allies against the Turks, the military faction of Uskoks was formed, which later became famous as an elite Croatian militant sect. Ultimately, the defenders were defeated and the fortress was occupied by the Ottomans in 1537. After more than a century under Ottoman rule, in 1669, Klis Fortress was besieged and seized by the Republic of Venice, thus moving the border between Christian and Muslim Europe further east and helping to contribute to the decline of the Ottoman Empire. The Venetians restored and enlarged the fortress, but it was taken by the Austrians after Napoleon extinguished the republic itself in 1797. Today, Klis Fortress contains a museum where visitors to this historic military structure can see an array of arms, armor, and traditional uniforms.