Alexander Guagnini (Polish: "Alexander Gwagnin" , Italian: "Alessandro Guagnini dei Rizzoni" ; 1538 in Verona, Republic of Venice – 1614 in Kraków, Polish-Lithuanian Commonwealth) was a Polish writer, military officer, chronicler and historian of Italian heritage.
 He is known as a Crown Rotmistrz of Poland and Commandant of Vitebsk.
 Guagnini fought for the Polish-Lithuanian Commonwealth in the Livonian War and the Moldavian Magnate Wars.
The Battle of Podhajce (October 6–16, 1667) was fought in the town of Podhajce in the Polish-Lithuanian Commonwealth (nowadays Pidhaitsi, western Ukraine), and the area surrounding it as part of the Polish-Tartar War and the Great Turkish War.
 The army of the Polish-Lithuanian Commonwealth under John III Sobieski, totaling around 9,000 men defeated Tatar and Cossack forces under Petro Doroshenko and Adil Giray, which totaled around 35,000 men.
A Treaty of Perpetual Peace (also "Treaty of Eternal Peace"; Polish: "Pokój wieczysty" or "Pokój Grzymułtowskiego", Russian: Вечный мир, Lithuanian: "Amžinoji taika" ) between the Tsardom of Russia and the Polish-Lithuanian Commonwealth was signed on 6 May 1686 in Moscow by Polish-Lithuanian Commonwealth envoys: "voivod" of Poznań Krzysztof Grzymułtowski and chancellor ("kanclerz") of Lithuania Marcjan Ogiński and Russian "knyaz" Vasily Vasilyevich Golitsyn These parties were moved to cooperate after a major geopolitical intervention in Ukraine on the part of the Ottoman Empire.
Joachim Chreptowicz pseud.: "Jeden z współziomków" (4 January 1729 – 4 March 1812), of Odrowąż Coat of Arms, was a Polish nobleman, writer, poet, politician, Grand Secretary of Lithuania, marshal of the Lithuanian Tribunal and the last Grand Chancellor of Lithuania.
 He was a member of the Permanent Council, activist of the Commission of National Education, physiocrat and a vivid supporter of the Targowica Confederation.
Denhof - is a Polish coat of arms.
 It was used by several szlachta families in the times of the Polish-Lithuanian Commonwealth.
 Dönhoff (German) or Denhoff (Polish) (sometimes also Denhof or Doenhoff) was a Livonian German noble family, a branch of which moved to the Polish-Lithuanian Commonwealth in the 16th century and became recognized as a Polish noble ("szlachta") there.
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.
The szlachta (Polish: "szlachta" , ) was a privileged social class in the Kingdom of Poland.
 The term "szlachta" was also used for the Lithuanian nobility after the union of the Grand Duchy of Lithuania with Poland as the Polish-Lithuanian Commonwealth (Union of Lublin, 1569) and for the increasingly Polonized nobilities of territories controlled by the Polish-Lithuanian Commonwealth, including Ducal Prussia and the Ruthenian lands.
The Warsaw Confederation, signed on January 28, 1573 by the Polish national assembly ("sejm konwokacyjny") in Warsaw, was the first European act granting religious freedoms.
 It was an important development in the history of Poland and Lithuania that extended religious tolerance to nobility and free persons within the Polish-Lithuanian Commonwealth and is considered the formal beginning of religious freedom in the Polish-Lithuanian Commonwealth.
 While it did not prevent all conflict based on religion, it did make the Commonwealth a much safer and more tolerant place than most of contemporaneous Europe, especially during the subsequent Thirty Years' War.
A konfederacja (] , "confederation") was an "ad hoc" association formed by Polish-Lithuanian "szlachta" (nobility), clergy, cities, or military forces in the Polish-Lithuanian Commonwealth for the attainment of stated aims.
 A konfederacja often took the form of an armed rebellion aimed at redressing perceived abuses or trespasses of some (e.g. royal) authority.
 Such "confederations" acted in lieu of state authority or to force their demands upon that authority.
 They could be seen as a primary expression of direct democracy and right of revolution in the Commonwealth, and as a way for the nobles to act on their grievances and against the state's central authority.
The Commission of National Education (Polish: "Komisja Edukacji Narodowej" , abbreviated KEN, Lithuanian: "Edukacinė komisija" , Belarusian: Адукацыйная камісія ) was the central educational authority in the Polish–Lithuanian Commonwealth, created by the Sejm and the King Stanisław August Poniatowski on October 14, 1773.
 Because of its vast authority and autonomy, it is considered the first Ministry of Education in European history and an important achievement of the Polish Enlightenment.

Question: Joachim Chreptowicz was an activist of what educational authority in the Polish-Lithuanian commonwealth?
Answer: Commission of National Education