House of Pernštejn
Although the Hussite wars and later the Bohemian–Hungarian wars brought medieval fortresses to unrelenting confrontation with the demands of contemporary warfare, the forts were not utterly doomed, but necessitated new views on their purposes.
No-one contemplated massive fortifications of small strongholds or castles in disadvantageous locations, unable to withstand artillery fire and mass attacks of the besiegers, but wealthy feudal lords did not hesitate to invest considerable resources into redevelopments and modifications of a smaller number of selected structures. Fortresses still seemed a necessity in Moravia in the troubled atmosphere of the 1470s, and with that belief, William of Pernštejn commenced the redevelopment of Helfštýn already in 1474. His initial construction plans were quickly implemented, and in 1480, he ordered a stone relief with the Pernštejn coat of arms on the new (second) gate, with an inscription about the progress of construction. Yet construction works continued until the early 16th century and attention to the military purpose side-lined all other aspects. This military purpose dictated, at Helfštýn as well as other late-Gothic castle conversions, respect to several basic requirements. Primarily, it was necessary to expand the castle premises and new outer baileys in order to allow construction of important farmhouses and utility buildings and make sufficient space to gather a large number of soldiers, if necessary. Secondly, it was necessary to adapt the fortifications system so the castle could effectively withstand artillery fire while returning their own gunfire. In the last quarter of the 15th century, Helfštýn Castle was expanded by a thoroughly fortified, sizeable outer bailey with farmhouses and utility buildings (finished by 1480) and another outer bailey as the forward defence of the whole expanded premises. The fortress was also perfected by bastions and a new system of towers and gates around the old castle. Most of these works were very technically demanding and they document to this day the level of craftsmanship as well as considerable costs expended by William of Pernštejn for the redevelopment of Hefštýn. The castle definitively took on its oblong shape and the flawless outer fortifications covering all other architectural elements.
Under William of Pernštejn (d. 1521), the Helfštýn domain became part of the largest holding in Moravia and Bohemia. Neither William of Pernštejn, nor his heirs had military ambitions and they tended their domains primarily in terms of economic gain, but after 1526, the year when the Turks invaded Hungary for the first time and threatened to invade Moravia as well, Helfštýn once again took on significant military importance. A stockpile of weapons, military equipment, and ammunition was collected at the castle, which was not only to defend the castle, but also equip the contingent of Pernštejn’s subjects for on-call military duties. The preserved castle inventory book from 1552 recorded a relatively low number of hunting weapons, but unprecedented numbers of weapons and ammunition, confirming the assumption that the armoury at Helfštýn also served other domains of the House of Pernštejn.