Question: The Königsberg fortifications were erected due to the vulnerability during which war of 1563-1721?

full_context: Document 1: Bell tower (Königsberg): The Bell tower in Königsberg (built by the architect Stüler) was a bell tower of the Schlosskirche (Königsberg). After being largely destroyed in World War II by Allied Forces and then annexed by the Soviet Union thereafter, the city was renamed Kaliningrad, and few traces of the former Königsberg remain today. As part of Königsberg Castle, the bell tower of the Schlosskirche (Königsberg) was devastated by the 1944 Bombing of Königsberg and 1945 Battle of Königsberg during World War II. The remnants were demolished in 1968, by which time the city was known as Kaliningrad.
Document 2: Military of the Swedish Empire: From 1611 to 1721, Sweden was a European great power, becoming a dominant faction in the quest for control of the Baltic Sea and a formidable military power. During this period, known as "Stormaktstiden" (Swedish: ""The Great Power Era"" ), the Swedish Empire held a territory more than twice the size of its modern borders and one of the most successful military forces at the time, proving itself on numerous occasions on battlefields such as Wallhof, Narva and Düna. The military of the Swedish empire is commonly (and wrongfully) recognized only as the Caroleans, which were in fact not in service until the late 17th century under Karl XI and his successor. The Swedish Empire and its modern military force was founded by Gustavus Adolphus, who inherited the throne in 1611 at age 17. He immediately reformed the common European military based on mercenaries to a professional national army. However, before completing his vision of conquering the Holy Roman Empire, the warrior king was killed in action in 1632. His daughter and successor did little to improve Sweden's military position and abdicated early, providing the Swedish Empire with a more warlike ruler. Karl X Gustav was only king for 5 years, but conquered large amounts of territory that still belong to Sweden today (including Blekinge, Bohuslän, Skåne and Halland). His son Karl XI would further strengthen the army by introducing the Caroleans, which were also used by Karl XII in the Great Northern War.
Document 3: Seventh Fort: The Seventh Fort or VII Fort is a defensive fortification built in Žaliakalnis district of Kaunas, Lithuania, during implementation of the first phase of the construction of the Kaunas Fortress. It is located near the Hospital of Lithuanian University of Health Sciences. This Fort became the last brick fortification of Kaunas Fortress. The Seventh Fort is close to the central defenses and it is located in the rear of Kaunas Fortress. The first owner of fort was the 11th company of Kaunas Fortress Artillery (Imperial Russian Army). In 1915, German Army occupied the Fort without resistance. The Seventh Fort is one of the best surviving examples of a two-rampart fort, showing the typical design of a 19th-century Russian brick fort. Many authentic elements survive, such as iron window frames, ammunition warehouse gate fragments. During the Fort's restoration, a number of authentic interior details (interior decoration, paving, fittings of ammunition storage doors and gate) were found.
Document 4: Ancient Roman defensive walls: Defensive walls are a feature of ancient Roman architecture. The Romans generally fortified cities, rather than fortresses, but there are some fortified camps, such as the Saxon Shore forts like Porchester Castle in England. City walls were already significant in Etruscan architecture, and in the struggle for control of Italy under the early Republic many more were built, using different techniques. These included tightly-fitting massive irregular polygonal blocks, shaped to fit exactly in a way reminiscent of later Inca work. The Romans called a simple rampart wall an agger; at this date great height was not necessary. The Servian Wall around Rome was an ambitious project of the early 4th century BC. The wall was up to 10 metres (32.8 ft) in height in places, 3.6 metres (12 ft) wide at its base, 11 km (7 mi) long, and is believed to have had 16 main gates, though many of these are mentioned only from writings, with no other known remains. Some of it had a "fossa" or ditch in front, and an agger behind, and it was enough to deter Hannibal. Later the Aurelian Wall replaced it, enclosing an expanded city, and using more sophisticated designs, with small forts at intervals.
Document 5: Krepost Sveaborg: The Krepost Sveaborg was an Imperial Russian system of land and coastal fortifications constructed around Helsinki during the First World War. The purpose of the fortress was to provide a secure naval base for the Russian Baltic fleet and to protect Helsinki and block routes to Saint Petersburg from a possible German invasion. Krepost Sveaborg was part of Peter the Great's Naval Fortress, a coastal fortification system protecting access to Saint Petersburg by sea. The central part of Krepost Sveaborg was the old fortress of Suomenlinna where the fortress headquarters were located. Due to technological advances in artillery the old fortress was no longer capable of providing a sufficient protection, and a new main defensive line was built well beyond the old fortress boundaries. New coastal artillery guns built on outlying islands protected Krepost Sveaborg from the sea, while fortified lines constructed around Helsinki were intended to stop any attacks on land. The primary coastal guns were 10 in model 1891 guns and 6 in model 1892 Canet guns. Older 11 in model 1877 guns were also used. In summer 1917 the fortress had two hundred coastal or anti-landing guns, of which 24 were 10-inch guns in six batteries, 16 were 6-inch Canet guns in four batteries and twelve were 11-inch guns in three batteries. The artillery used in land fortifications included older coastal guns, old fixed carriage guns and newer light field guns. In March 1917, Krepost Sveaborg had a total of 463 guns, although many of them were obsolescent. Krepost Sveaborg was still partly incomplete in 1917 when the February Revolution halted most of the construction work. Some further construction work was carried out during the remaining year, but all work halted during the October Revolution. Following the Finnish Declaration of Independence, parts of the land fortifications were used in the Finnish Civil War. The coastal fortifications were later taken over by Finland to protect Helsinki, while the land fortifications were mostly abandoned and disarmed.
Document 6: Polish–Swedish wars: The Polish–Swedish Wars were a series of wars between the Polish–Lithuanian Commonwealth and Sweden. Broadly construed, the term refers to a series of wars between 1563 and 1721. More narrowly, it refers to particular wars between 1600 and 1629. These are the wars included under the broader use of the term:
Document 7: Russo-Polish War (1654–1667): The Russo-Polish War of 1654–1667, also called Thirteen Years' War, First Northern War, or the War for Ukraine, was a major conflict between Tsardom of Russia and the Polish-Lithuanian Commonwealth. Between 1655 and 1660, the Second Northern War was also fought in the Polish-Lithuanian Commonwealth, thus this period became known in Poland as "The Deluge". The Commonwealth initially suffered defeats, but regained its ground and won most of the battles. However its plundered economy was not able to fund the long conflict. Facing internal crisis and civil war, Poland was forced to sign a truce. The war ended with significant Russian territorial gains and marked the beginning of the rise of Russia as a great power in Eastern Europe.
Document 8: Battle of Königsberg: The Battle of Königsberg, also known as the Königsberg Offensive, was one of the last operations of the East Prussian Offensive during World War II. In four days of violent urban warfare, Soviet forces of the 1st Baltic Front and the 3rd Belorussian Front captured the city of Königsberg – now Kaliningrad, Russia. The siege started in late January 1945 when the Soviets initially surrounded the city. There was heavy fighting for the overland connection between Königsberg and the port of Pillau, but by March 1945 Königsberg was hundreds of kilometres behind the main front line. The battle finished when the German garrison surrendered to the Soviets on 9 April after a three-day assault made their position untenable.
Document 9: War of the Polish Succession (1587–88): The War of the Polish Succession or the Habsburg-Polish War took place from 1587 to 1588 over the election of monarch after the death of King of Poland and Grand Duke of Lithuania Stephen Báthory. The war was fought between factions of Sigismund III Vasa and Maximilian III, with Sigismund eventually being crowned King of Poland and Grand Duke of Lithuania. Two major battles of this conflict included the Siege of Kraków, in which Maximilian III failed to capture the capital of the Commonwealth, and the Battle of Byczyna, in which Maximilian was forced to surrender. Sigismund's victory was significantly the doing of Chancellor and Hetman Jan Zamoyski, who stood behind both the political intrigue and the military victories of this conflict.
Document 10: Königsberg fortifications: The fortifications of the former East Prussian capital Königsberg (now Kaliningrad) consist of numerous defensive walls, forts, bastions and other structures. They make up the First and the Second Defensive Belt, built in 1626—1634 and 1843—1859, respectively. The 15 metre-thick First Belt was erected due to Königsberg's vulnerability during the Polish–Swedish wars. The Second Belt was largely constructed on the place of the first one, which was in a bad condition. The new belt included twelve bastions, three ravelins, seven spoil banks and two fortresses, surrounded by water moat. Ten brick gates served as entrances and passages through defensive lines and were equipped with moveable bridges.
Document 11: Battle of Gniew: The Battle of Gniew or the Battle of Mewe was fought during the Polish–Swedish War (1626–1629), between Sweden and the Polish–Lithuanian Commonwealth from 22 September with initial skirmishes, to the main battle of 1 October 1626. Both the Swedish and Polish army were commanded by their kings – Gustavus Adolphus of Sweden and Sigismund III Vasa. The battle ended with a victory for Sweden. However, Polish and Swedish armies had different objectives. Sigismund Vasa wanted to protect Gdańsk from besieging. Gustav had to protect Gniew, which was important for the prestige for his army.
Document 12: Polish–Ottoman War (1683–99): Polish–Ottoman War (1683–1699), the Third Polish–Ottoman War or the War of the Holy League refers to the Polish side of the conflict otherwise known as the Great Turkish War. The conflict begun with a great Polish victory at the battle of Vienna in 1683, and ended with the Treaty of Karlowitz, restoring to the Polish–Lithuanian Commonwealth lands lost in the previous Polish-Ottoman War (the Polish–Ottoman War (1672–1676)). It was the last conflict between the Polish–Lithuanian Commonwealth and the Ottoman Empire, and despite the Polish victory, it marked the decline of power of not only the Ottoman Empire, but also of the Commonwealth, which would never again interfere in affairs outside of its declining borders.
Document 13: Swedish intervention in the Thirty Years' War: The Swedish invasion of the Holy Roman Empire, or the Swedish Intervention in the Thirty Years' War is a historically accepted division of the Thirty Years' War. It was a military conflict that took place between 1630 and 1635, during the course of the Thirty Years' War. It was a major turning point of the war, as during this time, the Protestant cause, previously on the verge of defeat, won several major victories and snatched victory away from the Habsburg-Catholic coalition. It is often considered to be an independent conflict by most historians.
Document 14: Polish–Swedish War (1600–11): The Polish–Swedish War (1600–11) was a continuation of struggle between Sweden and Poland over control of Livonia and Estonia, as well as the dispute over the Swedish throne between Charles IX of Sweden and Sigismund III of Poland.
Document 15: Varugad: The hill rises about 250 feet above the level of the plateau, which itself constitutes the summit of the Mahadev range at this point. The cone with the walls on it is seen from a great distance and appears very small indeed. But on near approach it is seen to be but the inner citadel of a place of considerable size and strength for the times in which it was built. On the south-west the outer wall or enceinte is entered by a rude gateway of a single pointed arch about eight feet high and five feet broad. As usual there is a curtain of solid masonry inside. The gate lies about 150 yards east of the edge of the plateau, which there terminates in an almost unbroken vertical precipice of several hundred feet in height and receding in a north-easterly direction. No wall was built along about three hundred yards of this part which is absolutely unscalable, but for the rest of the way the walling is continued along the edge of the cliff in a north-east direction for about another three hundred yards. Here it turns still following the cliff to the south-east for another seven hundred yards, and then gradually rounds to the westward covering four hundred and fifty yards more till it meets the gateway. But for the break of the inaccessible precipice this outer wall would form a nearly equilateral triangle with the corners rounded off, the side being of some six hundred and fifty yards. Facing nearly north, about fifty yards from the north-east angle, is a gateway with a couple of curtains in solid masonry. This entrance is cut in the sides of the cliff about twenty feet below the top which is reached by some dozen steps. It consisted as usual of a pointed arch, the top fallen in, about ten feet high by five broad. It leads out to the path down to Girvi, a village in the plains below and it probably formed the communication with Phaltan. This road winds down the face of the range for some five hundred feet till it hits the shoulder of a spur which it then follows to the base. The walling on the south side, from the edge of the cliff to some hundred yards east of the southern gate, is not more than a couple of feet in thickness and consists of all-fitting stones unmortared. The rest is massive and well mortared and still fairly preserved. The average height is from seven to ten feet. In the south-east angle is a rude temple of Bhairavnath and a few houses with the remains of Man y more. On the right side of the southern gate is a well preserved stone pond about thirty yards square with steps leading down to it. Next to and on the north of Bhairavnath's temple is another pond. The way up to the fort proper or upper and lower citadels is from the north side. The path up the hill side, which is steep but with grass and soil left in Man y places, is almost destroyed. About 150 feet up is the outer citadel built on a sort of shoulder of the hill and facing almost due west. It contains two massive bastions of excellent masonry looking north-west and south-west so that guns planted on them could comMan d respectively the north and south gateways. This citadel was connected with the main wall by a cross wall running across the whole breadth of the fort from east to west. Its entrance lies close below that to the upper citadel. A masonry curtain projects so as to hide the arch itself, which is not more than seven feet high by three broad, and has to be entered from due east. On the south side the walls are carried right up to the scarp of the upper citadel and are some ten feet high, so that to take the lower citadel in rear or flank must have been difficult. The upper citadel is above a vertical scarp some thirty feet high. The entrance to it lies some thirty feet above that to the lower citadel, and is cut in the rock about eight feet wide. There is a gateway of a pointed arch with the top fallen in and twenty odd steps leading up to it and ten more cut out of the rock, and winding up past the inside curtain on to the top. The walls of this upper citadel are still in tolerable preservation. They were originally about ten feet high and built of fair masonry. There is a large turret on the south-west corner, evidently meant to comMan d the southern gate. About ten yards to the east of this turret is a new looking building which was the headquarters or sadar. Immediately east of this and below it is a great pit about thirty feet square and equally deep roughly cut in the rock and said by the people to be a dungeon. Next to it on the south is a small pond evenly cut and lined with mortar used for storing water. There are some remains of sepoys' houses, and, near the turret, a small stone wheel said to belong to a gun. The outer walls east of the gates have bastions at every turn of the cliffs, and the masonry here is particularly strong and well preserved. It would appear that attacks were dreaded chiefly from the plain below. The assailants could either come up the spur towards the north entrance or they might attempt the spurs on the other side of the eastern ravine and attack the southern gateway. Hence apparently the reason for strengthening the walls of the enceinte on this side. After passing the southern gateway the assailants would be commanded Maan, Maharashtra from the lower citadel. They Would then be encountered by the cross wall. If that obstacle was overcome the besieged would run round the east side and into the two citadels. The appearance from the fort of the plain in the north is most formidable. The Panvan plateau completely commands Maan, Maharashtra and almost overhangs it. The fort is believed to have been built by Shivaji to resist the Moghals whose attacks he must have dreaded from the plain below. The Karkhanis or Superintendent of the fort was a Prabhu. The fort garrison consisted of 200 Ramoshis, Mahars, and other hereditary Gadkaris besides sepoys. It was surrendered in 1818 to Vitthal Pant Phadnis of the Raja of Satara left in charge of the town. He detached 200 men to take possession, being part of a force then raised to protect the town from the enterprizes of Bajirav's garrisons then in the neighbourhood. [Elphinstone in Pendhari and Maratha War Papers, 245.]
ground_truth: The Polish–Swedish Wars