Built through the efforts of King Wladyslaw IV and Great Crown Hetman Stanislaw Koniecpolski, the Kudak fort on the Kojdac pooh on the Dnieper was the second fortification in the borderlands of the Polish-Lithuanian Commonwealth. It replaced a small redoubt that had existed there a few years earlier, destroyed by Zaporozhian Cossacks. The purpose of the construction of both fortifications was to prevent irritation with the Ottoman Ports, which accused the authorities of the Republic of tolerating armed Cossack incursions (chadzek) into the cities of the Turkish Black Sea coast. The fort was intended to prevent the Zaporozhians from supplying men and military equipment to the permanent Zaporozhian military camp on Chortitsa Island on the Dnieper (south of Kudak), from where the Cossacks undertook their plundering expeditions.

Johan Pleitner - military engineer of King Vladislav IV, captain of the guard
. In order to build a real fortress, the king, in agreement with Hetman Stanisław Koniecpolski, delegated his military engineer Johann Pleitner, already experienced in the Smolensk War (1633-1634). He assigned another specialist, Friedrich Getkant, to assist him. Earthworks began in Kudak in August 1639, with the forces of soldiers from the Crown army and peasants from Hetman Koniecpolski's Ukrainian estates.

Johann Pleitner (c. 1605-1664), captain of the royal guard and military engineer to King Wladyslaw IV, drew up a plan of the four-bastion fort on the site, and skilfully used the terrain conditions of the high bank of the Dnieper. On the side of the rocky river bluff, a zigzag line of ramparts (the so-called ticks) and two half-bastions fitted into the local hills. The artillery placed there controlled the movement of the Cossack boats (chajki) pushing through a narrow isthmus in the poroh (river sill) of the Kojdac. In the south, on the other hand, the fortress was guarded by two full bastions on the side of the terrain, which was considerably lowering.

Kudak - an impregnable Polish borderland fort ress
The fort was roughly square in plan with dimensions of about 207 x 200 metres at the tips of the bastions. It was possible to get drinking water from the Dnieper River via two staircases protected by palisades.

The ramparts had a total length of about 850 metres and a height of about 9 metres. A moat 12 metres wide and 7 metres deep was made around the ramparts on the land side. In its foreground, a so-called forebay, 20 metres wide and 3 metres high, was constructed, additionally protected from the outside by a 2-metre-deep ditch.

A separate fortification was a triangular ravelin with its own moat, located opposite the south-eastern curtain (the rampart between the bastions), which additionally protected the fort from possible enemy attack from a deep ravine leading to the river. A palisade was driven in front of the rampart on the landward side and the area was strewn with boulders hewn from the rocky shore.

A road led to the inside of the fort, via a wooden bridge over the moat, through the Krylov gate (named after the nearby town of Krylov). In the courtyard of the fort there was a small church, the garrison commander's house and dugout-like barracks for the several hundred-strong garrison.

The fort was equipped with a dozen or so regimental cannons (some of which were Moscow cannons captured after Mikhail Shein's surrender at Smolensk in 1634). A powerful fortress was created, which King Władysław IV proudly described in a letter to Hetman Koniecpolski with the words: Our Transnistrian Fortress. With the fate of the redoubt destroyed by the Cossacks in mind, no regimented Cossacks (in the service of the Republic) were accepted for service in the Kudak garrison (400-600 soldiers), but only Polish and German infantry. Kudak was also the official Crown arsenal, where armaments and gunpowder were stored.

The turbulent history of the Kudak fortress
Less than 3 kilometres south-west of the fort, a tall watchtower was built with a small garrison of about a hundred soldiers. It was used to alert Kudak in case Cossack wads were detected sneaking into Sich. At the beginning of the 20th century, there was still the village of Nemtytskaya, probably named after a German infantry unit stationed there at one time.

Cossack siege of the Kudak fortress during the Khmelnytsky uprising
. The Kudak fort proved its high defensive value, withstanding an almost five-month siege by the Cossack rebels of Bohdan Khmelnytsky in 1648. It was not until the news of the shameful defeat of the Crown army and private troops at Piławce in September 1648, and the incursion of Khmelnytsky's troops as far as Lviv and Zamość, that Krzysztof Grodzicki, the fortress commander, was forced to capitulate in honour on 1 October 1648.

Sad end of the Kudak fort
The Khmelnytsky uprising put an end to the Kudak fortress within the borders of the Republic. The fort was used by the Zaporozhian Cossacks as a logistical base for troops in the lower reaches of the Dnieper, and later by the Russians, who captured left-bank Ukraine.

The ramparts of the fort survived until 1944, when the Soviet authorities began plundering the area as a quarry. Remnants of the two southern bastions and parts of the curtains have survived to the present day. In 1910, a Russian memorial obelisk was erected on the rampart in honour of Bohdan Khmelnytsky, and in the 1990s a Ukrainian information board and stone steles celebrating Cossack heroism were erected.