A borderland that had to be guarded

Lower Silesia was so densely fortified because for centuries it lay at the crossing point of the interests of several states. The region belonged in turn to the Silesian Piasts, Bohemia and the Habsburgs, until as a result of the Silesian Wars in the mid-18th century it passed under Prussian rule. For King Frederick the Great and his successors it was territory only recently conquered, bordering to the south on the mountain range of the Sudetes, beyond which lay a hostile Austria still hoping to win the province back. Hence the decision to build a belt of fortifications along the border passes and roads leading from the Bohemian side of the mountains into Silesia.

Work on the largest structures was led by engineers such as Ludwik Wilhelm Regeler, the author of the design for Srebrna Góra Fortress, personally revised by Frederick the Great, and Captain Engineer Ludwig Müller, responsible for the smaller border forts in the Bystrzyckie Mountains.

Prussian forts on the border with Austria

Alongside the great fortresses to which the portal has devoted separate articles, on the border hills of the Sudetes Frederick William II ordered the construction of a network of smaller forts with small garrisons, guarding specific roads and passes rather than standing as self-sufficient strongholds capable of withstanding a long siege.

Fort Fryderyka was built between 1790 and 1795 on the western summit of Kamienna Góra in the Bystrzyckie Mountains, near Pokrzywno close to Polanica-Zdrój. Not far away, in the same mountains, Fort Wilhelma was erected at the same time, designed by Captain Ludwig Müller. The fort played no significant role during the Napoleonic Wars, its garrison abandoned it in 1806, and at the end of the 19th century the structure was demolished - the stone recovered from it was used to build a railway viaduct and a school in nearby Bystrzyca Kłodzka.

On Góra Ptak in the Table Mountains, near Karłów, a small guardhouse known today as Fort Karola was built in 1790. It had a garrison of a few men and guarded the road to Radków, known today as the Szosa Stu Zakrętów (Road of a Hundred Bends).

A separate episode is the fort at Szalejów Górny, built at the turn of 1778 and 1779, even before the series of forts built by Frederick William II, during the War of the Bavarian Succession - a timber-and-earth obstacle meant to slow the enemy's advance. On 17 January 1779 it was attacked by Austrian troops under Field Marshal Dagobert Sigmund von Wurmser. It was defended by a sixty-strong garrison under Captain Capellery and successfully delayed the assault, although nothing of the structure itself remains visible on the ground today.

The fortifications from the era of the Silesian Wars also include the hillfort on Forteczna in Rościszów in the Owl Mountains, where at an altitude of 535 metres an earthen rampart and moat survive, partly dating from the Middle Ages and partly added by Austrian troops during the Seven Years' War in the 18th century.

The region's largest fortifications - Kłodzko Fortress and Srebrna Góra Fortress, regarded as the largest mountain fortress in Europe never to have been captured - are covered by the portal in separate articles.

Town walls disappear, hills and parks remain

Alongside the border forts, the towns of Lower Silesia had been surrounded by their own defensive walls since the Middle Ages. Some of these survived in good condition, such as the town walls of Świebodzice, originally more than 900 metres long and considered one of the best-preserved medieval town fortifications in Poland. In Wrocław things went differently: the town's defensive walls were torn down on the orders of the French occupiers in 1807, during the Napoleonic Wars. On the site of one of the bastions, called Bastion Sakwowy, a recreational hill was created, supplemented in 1867 with a belvedere and an observation tower. It operated under the German name Liebichs Höhe, and after the war as Wzgórze Partyzantów (Partisans' Hill), with the historic name Bastion Sakwowy only restored to it in the 21st century. Today Wzgórze Partyzantów is the tenth-highest hill in Wrocław, and it is hard to guess that a fortification stood here as recently as the early 19th century. Demolishing town walls in the 19th century, once they had lost their military significance and had begun to restrict urban growth, was common practice in Prussia - fortifications survived where they stood out of the way, like mountain fortresses, or were converted to a different use, like the Wrocław bastion.

The 20th century: fortresses meant to hold out to the end

In the Nazi era the term fortress returned to the Silesian vocabulary, though in a completely different sense than in the 18th century. In August 1944 Hitler declared Wrocław a fortress (Festung Breslau), many months before the siege began. The decision was formally confirmed by Gauleiter Karl Hanke on 20 January 1945, triggering the evacuation of the city and the conscription of men aged 16 to 60 - women and children had to leave the city on foot, in temperatures of around minus twenty degrees. The siege of Wrocław lasted 82 days, from 13 February to 6 May 1945, and destroyed a large part of the city, including the Chapel of the Blessed Virgin Mary, the Church of St John and the Brothers Hospitallers' monastery. Głogów was declared a fortress in the same way - the aim was to slow the advance of the Red Army, which led to the destruction of around 95 per cent of the town's buildings.

Historic fortifications from the 18th and 19th centuries were put to new uses during this period. Between 1940 and 1943, Kłodzko Fortress operated as a subcamp of the Gross-Rosen concentration camp, holding prisoners including Russians, French, Italians, Belgians, Czechs, Finns and Britons, and from 1944 it housed AEG plants evacuated from Łódź, producing components for V-1 rockets and electrical equipment for submarines and aircraft. The 19th century also produced the ring of forts surrounding Wrocław, built as part of the Prussian system for defending the city. One of them, on today's Pełczyńska Street in Lipa Piotrowska, has been opened to visitors as Fort Wrocław No. 9 - its casemates house a community-run military museum with the exhibition "Breslau 1808-1950 Wrocław" and outdoor exhibits including a T-55 tank.

What can be visited today, and in what condition

The state of preservation of Lower Silesia's fortifications varies enormously. At one extreme are sites fully adapted as museums, such as Kłodzko Fortress and Srebrna Góra Fortress, where visitors can walk kilometres of corridors and see reconstructed interiors, and Fort Wrocław No. 9, which can only be visited in organised groups with a guide.

At the other extreme are ruins visible today only as outlines in the terrain. Only remnants survive of Fort Karola on Góra Ptak, and the sources do not even state whether the site is currently marked as a hiking trail - this is worth checking at the local tourist information point before setting out. The same applies to Fort Wilhelma, of which only the outline of a rampart, a partly filled-in moat and fragments of walls hidden in a spruce forest remain, and to the fort at Szalejów Górny, of which no visible traces survive today, even though it is the only structure of this type in the Kłodzko Land actually used in combat. The hillfort on Forteczna in Rościszów retains a legible layout of rampart and moat, but requires a walk along a trail in the Owl Mountains, with no tourist infrastructure on site. The smaller border forts have never become destinations in their own right - they are points along mountain hiking routes through the Sudetes, worth visiting along the way, unlike the great fortresses at Kłodzko and Srebrna Góra.