The Battle of Berestechko (; ) was fought between the Ukrainian Cossacks, led by Hetman Bohdan Khmelnytsky, aided by their Crimean Tatar allies, and a Polish-Lithuanian Commonwealth army under King John II Casimir.

George was married at Dresden, on 21 November 1496, to Barbara Jagiellon, daughter of Casimir IV, King of Poland and Elisabeth, daughter of Albrecht II of Hungary.

This was followed by a collapse of the monarchy and restoration under Casimir I. Casimir's son Bolesław II the Bold became fatally involved in a conflict with the ecclesiastical authority, and was expelled from the country.

The government became ineffective because of large scale internal conflicts ( e. g. Lubomirski's Rokosz against John II Casimir and rebellious confederations ), corrupted legislative processes and manipulation by foreign interests.

There were descendants of superseded daughters of Casimir III of Poland ( d. 1370 ), such as his youngest daughter Anna, Countess of Celje ( d. 1425 without surviving Issue ), and her daughter Anna of Celje ( 1380 – 1416 ) whom Władysław II Jagiełło married next.

Among them were Boleslaw IV the Curly, Mieszko III the Old, Casimir II the Just, Leszek I the White, Boleslaw V the Chaste, Leszek II the Black, Wladyslaw I the Elbow-high, and King of Bohemia, Wenceslaus II of Bohemia, who united Lesser Poland in 1290 / 1291.

* 1609 – King John II Casimir of Poland ( d. 1672 )

Poznań's cathedral was the place of burial of the early Piast monarchs ( Mieszko I, Boleslaus I, Mieszko II, Casimir I ), and later of Przemysł I and King Przemysł II.

The doctoral thesis, accepted by King John II Casimir University of Lwów in 1920 and published in 1922, included the basic ideas of functional analysis, which was soon to become an entirely new branch of mathematics.

* March 22 – John II Casimir of Poland ( d. 1672 )

* Casimir II of Poland succeeds Boleslaus IV of Poland on the throne.

* Elisabeth ( 1438 – 1505 ), who married Casimir IV of Poland, and whose son Vladislaus II of Bohemia later became king of Bohemia and Hungary

* December 6 – King John II Casimir of Poland ( b. 1609 )

However, not all the Silesian dukes accepted his authority: Dukes Bolko I the Strict, Konrad II the Hunchback and three of the four sons of Władysław of Opole: Casimir of Bytom, Mieszko I of Cieszyn and Przemysław of Racibórz were completely against Henry's politics.

* May 5 – King Casimir II of Poland ( b. 1138 )

* Casimir II of Poland ( d. 1194 )

* Casimir II becomes duke of Poland.

Richeza's son Casimir was at that time at the court of his maternal uncle Hermann II, Archbishop of Köln.

In Saalfeld Richeza led the Polish opposition which supported her son Casimir, who in 1039, with the help of Conrad II, finally obtain the Polish throne.

Following the abdication of King John II Casimir Vasa and the end of The Deluge, the Polish nobility elected Michał to the Polish throne.

A promising commander, John was sent by King John II Casimir to Istanbul in the Ottoman Empire as an envoy.

# John Casimir (; 22 May 1609 1672 ), reigned 1648 – 1668 as John II Casimir Vasa of Poland

It was not until 1997, however, that a direct experiment, by S. Lamoreaux, described above, quantitatively measured the force ( to within 15 % of the value predicted by the theory ), although previous work van Blockland and Overbeek ( 1978 ) had observed the force qualitatively, and indirect validation of the predicted Casimir energy had been made by measuring the thickness of liquid Helium films by Sabisky and Anderson in 1972.

When the anti-Swedish coalition however gained the upper hand, Frederick William changed sides when Polish king John II Casimir Vasa confirmed his sovereignty in Prussia, but not in Ermland, in the Treaty of Wehlau-Bromberg in 1657.

George however anticipated all his enemies by suddenly excluding his own son from the throne in favour of Ladislaus, the eldest son of Casimir IV, thus skillfully enlisting Poland on his side.

On 29 June however, Warsaw was stormed by John II Casimir, who had drawn up to Charles X Gustav with a force of 28, 500 regulars and a noble levy of 18, 000 to 20, 000.

The treaty was however renewed and amended on 27 May by Ferdinand's successor Leopold I of Habsburg, who agreed in Vienna to provide John II Casimir with 12, 000 troops maintained at Polish expense ; in return, Leopold received Kraków and Posen in pawn.

The formal treaty was signed on 29 November 1259 ; however, Casimir I delayed in fulfilled the provisions of the agreement, which led in 1261 to a new military expedition.

General immigration of German settlers diminished, however, when Poland under Casimir IV Jagiellon ( Kazimierz, 1447 – 92 ) defeated the Teutonic Order in 1466.

The town of Chrzanów was built according to the Magdeburg Law in the mid-14th century under the reign of King Casimir III the Great, however, nothing proves that it was surrounded by defence walls.

Later in 1388 however, the dukes of Pomerania-Stolp left this alliance and sided with Poland, who had promised to partially respect their claims as Casimir III's heirs.

Jutta was originally betrothed to Casimir III of Poland, however this arrangement was broken and Casimir married Aldona of Lithuania instead.

After Aldona's death, Casimir was betrothed to Jutta's elder sister Margaret, however this betrothal was also broken and Casimir remarried to Adelaide of Hesse.

It was not, however, until the Treaty of Radnot of late 1656, when in early 1657, as the ally of Charles X Gustav, that he led a force of 40, 000 men against the Polish king, John Casimir in the third part of Second Northern War ( 1655-1660 ), also known as The Deluge.

Casimir, eager to defend Christianity against the Turks, accepted the offer and went to Hungary to obtain the crown.

After initially escaping to Hungary, Casimir went to Germany, where in 1039 his relative the Emperor Henry III ( who feared the increased power of the Bohemian ruler ) gave him military and financial support.

In order to enlist the support of the nobility, especially the military help of pospolite ruszenie, Casimir was forced to give up important privileges to their caste, which made them finally clearly dominant over townsfolk ( burghers or mieszczaństwo ).

However, Casimir III the Great submitted to the Golden Horde and undertook to pay tribute in order to avoid more conflicts.

The Polish King, Casimir III the Great, submitted to the Horde and undertook to pay tribute in order to avoid more conflicts.

Taking offence at this, John Casimir in 1638 left for Spain to become Viceroy of Portugal, but was captured by French agents and imprisoned by order of Cardinal Richelieu until 1640.

In 1651, the Dutch under Peter Stuyvesant established Fort Casimir at present-day New Castle, only 7 mi ( 12 km ) south of Fort Christina, in order to menace the Swedish settlement.

The monument was moved in the mid 1970s in order to accommodate widening of the original QEW, and is now located in the nearby Sir Casimir Gzowski Park along Lake Ontario, on the east side of the Humber River.

The earliest documents which corroborate the existence of Chrzanów castellany come from the late 12th century when in around 1178 Chrzanów castellany was annexed to Silesia by order of Duke Casimir II the Just.

Janusz Radziwiłł used his political influence against the King of Poland and the Grand Duke of Lithuania John II Casimir in order to secure the offices of voivode and hetman.

During the night, John II Casimir realized that victory was unattainable and decided to evacuate the baggage train and his infantry across the Vistula River, while the cavalry was to prolong the fighting in order to cover the retreat and then withdraw south along the river.

When the artillery and infantry was across the bridge, John II Casimir ordered it to be burnt down in order to halt the pursuing Brandenburg cavalry.

By the order of Casimir Jagiellon, the Principality of Kiev was abolished and the Kiev Voivodship was established in 1471.