The fortress in Bač is the most important and best preserved medieval fortress in Vojvodina. The site where the fortress is built testifies to centuries long use of this naturally tenable ground which tied its fate to the Danube River - a natural border between nations and civilizations.
Very rich Avar necropoli were recorded in the surroundings Bač. In the Salzburg chronicle from 873 there is a reference to the areas between the Danube and the Tisa, settled by the Slavs, Avars, Huns, and the fact that the fortress was held by the Avars. It still has not become clear about the presence and role of the Slavs and barbarian colonization, nor the continuity of the early church organization established in this area.
The arrival of the Hungarians in the Pannonian Plain in 896 set new relations and in subsequent centuries Bač became an important historical place, often in the possession of the Hungarian kings. Together with Kaloč, it was the seat of the archdiocese, a popular entertainment venue visited by many European rulers. Since it was located on the southern border of Hungary it was administered under the authority of the Byzantine Empire. There was also cooperation and conflict with Serbia in the period of Nemanjić family. Especially significant was the role of Bač in the defense of Western Europe from the advance of the Turks.
Hungarians found the fortress earthy while Anonimus called it "old". During the mid-twelfth century Bač was so significant that the Arab geographer Idrizi in 1154 marked it in Roger’s map of the world the "Geography" – a book that tracks maps. There Idrizi wrote: " Bač is a glorious place included among other big towns. There are markets, trade shops, many artisans and Greek scientists ... Wheat is cheap however, as it can be found in abundance ... Bač and Kovin are very large export populated towns. They are the main towns of the Hungarian country with the majority of buildings. People live in the greatest abundance on the largest rural properties.
The period between 1338 and 1342, when king Charles Robert Anjou strengthened the border of the kingdom, is connected with the formation of a part of today’s fortress. This is the time of the rise of Emperor Dušan and the Serbian - Hungarian wars, as King Charles mentioned in a letter as a threat and the reason for undertaking the work on the fortress in Bač. The strengthening and upgrading of the fort lasted for almost two centuries. Work on strengthening and adapting the fortress to new military and engineering requirements was led by archbishops who were often prefects. Efforts of Peter Varadi II, a humanist, scholar and art lover who rounded architectural oeuvre and deepened defense water trenches around the fort in the period between 1495 and 1501 are recorded. In one of the letters sent from Bač, the Archbishop wrote: "We can enjoy the purest Danube water, and if Narcissus were alive, he would be able to enjoy looking at this image in the water!" Last reconstruction, before the Ottoman rule, was during the time of Father Paul Tomori (1523 – 1526). The defensive system was then completed and could look as follows.
Suburbium of the fortress, surrounded by palisades, was located on a naturally elevated terrain formed by the meandering of the river Mostonga, in the direction of east to west. The town was entered by bridge and through the front gate of the tower. In the northwestern part of the meander, there was a fortified castle located on the island. The castle could be reached by passing through a separated barbican surrounded by water from all sides. The plateau where the fortress is built is relatively small in size and covers an area of 8,700 m2. The basis of the fortress, measuring 5,600 m2, has a trapezoid shape adjusted to the terrain. There were five protruding defence towers with firing lanes on the corners connected by a 2.5 m wide and 12 m high rampart. The towers were different shapes and sizes. Three corner towers have a circular base open towards the inner space, while the northwest tower and the tower with an entrance gate had a rectangular base. The eastern part of the fortress was best defended, since there was a defensive - donjon tower with a residential palace, a well and a cistern. Buildings for different purposes leant against the inner side of ramparts - palaces, economic structures along the western rampart and a number of grain pits. All the buildings were constructed of brick with stone used for decorative elements.
On the outside, the fortress looked well-fortified, powerful, beautifully shaped and dominated the fertile plains of Bačka. A circular tower with balconies on stone consoles was drawing special attention. A tower with a Gothic chapel on the first floor stood out inside the fortress, as well as the donjon tower - the most dominant object of the fortress. The donjon tower had a regular square base and was oriented diagonally to the sides of the world, with a separate spiral staircase in the north-western façade and protruding toilets on the northeast facade. Palaces were adorned with terracotta elements made in the spirit of the early Italian Renaissance.
The first time Bаč fell into Turkish hands was in 1526 after the Battle of Mohač when the Turkish army was led by Sultan Suleiman the Magnificent. The role of the Serbian "Emperor" Jovan Nenad, who won Bаč back in 1527, was noted as well as the fact that after his death, Serbian despot Stefan Berislavić tried to strengthen the defense system in this part of the Danube. Turks finally occupied Bačka fortress in 1529, but the government was established after 14 years. In the long period of Turkish domination the fortress was in deep behind with small crew. Extensive mobile material evidence found in archaeological excavations in silos testify to the intensive use of the fortress. Valuable information about Bač, the fortress and the suburbium was left by Evliya Çelebi. During a visit to Bač in 1665, among other things he noted this: "It's a great fortress on a lake that receives water from the Danube; it has a rectangular shape and it is made of brick ... In this town there is another big tower – a real cosmorama facing the lake. There is a wonderful rest area like the emperor’s. It's a castle as beautiful as Havernek where all enlightened and sincere friends of the town meet to relax and have fun".
Judging by documents and old engravings, the town did not suffer severe damage during the liberation from the Turks in 1686. However, the big changes that followed did not benefit Bačka or many other medieval fortresses!
During the Rakocije uprising Bač suffered heavy losses and the fortress was destroyed several times by fire while passing from Kuruc rule to the Habsburg imperial army, and vice versa. After being blasted in 1704, the fortress was abandoned. Being unable to be used for defense, the fortress began to live a new life – as a glorious ruin. It was especially interesting to treasure seekers and those who were taking brick and stone for almost two and a half centuries.
The fortress also attracted the attention of researchers. Within the collapsed walls original medieval forms important for understanding architecture and life remained. Therefore, the fact that it was no longer expanded nor rebuilt in order to adjust to the military technology development contributed to its importance as a piece of cultural heritage.
In 1948, the fortress in Bač got the status of a cultural monument, which has stopped further deterioration and removal of materials and opened the way to an organized care for its preservation.
Even the researches back in the 19th century pointed to the value of the fortress in Bač. The first organized excavations were conducted by Imre Henzlman in 1870 and 1872, leaving valuable texts illustrated with drawings of the fortress and archaeological material. He also made proposals for the ideal reconstruction of certain buildings. In 1939 Rudolf Schmidt and Đurđe Bošković published an extensive work that draws attention to the values and characteristics of Bačka fortress.
The area of the former suburbium, which begins with a gate tower and ends with a fortified castle, had a somewhat different fate to the fortress which was declared a cultural monument. In the mid 60s of the 20th century, a canal was dug and a whole remained without water trenches and fortresses without a water mirror. The street in the historic suburb lost connection with Bač. Old houses have changed authentic forms and materials over time. Long did the process of determining the value of the whole, and that process is still going on, although in the meantime the fortress, together with a suburbium, has been declared a cultural and historic unity of great significance for the Republic of Serbia.
Slаvicа Vuјоvić, Tvrđave i ostaci utvrđenih gradova - Bаč, Publikacija 09, JP ''Bеоgrаdskа tvrđаvа'', (2008); Slavica Vujović, “Integrativna zaštita prostorne kulturno-istorijske celine Tvrđava i podgrađe u Baču”, in: Urbana regeneracija zaštićenih ambijentalnih celina u kontekstu održivog razvoja – Podgrađe Tvrđave Bač, Beograd: Arhitektonski fakultet, 2011, 108-142 (http://obavezni.digital.nb.rs/izdavac/af/publikacija/11)