Andrei of Polotsk (Belarusian: Андрэй Альгердавіч , Lithuanian: "Andrius Algirdaitis" Polish: "Andrzej Olgierdowic" , ca. 1325 – 12 August 1399, in the Battle of the Vorskla River) was the eldest son of Algirdas, Grand Duke of Lithuania, and his first wife Maria of Vitebsk.
 He was Duke of Pskov (through his deputy Yuri, 1342–1348) and Polotsk (1342–1387).
 As the eldest son of the Grand Duke, Andrei claimed his right to the throne after his father's death in 1377.
 Algirdas left Jogaila, his eldest son with his second wife Uliana of Tver, as the rightful heir.
 Andrei's rivalry with Jogaila, Grand Duke of Lithuania and later King of Poland, eventually led to his demise.
The Union of Horodło or Pact of Horodło was a set of three acts signed in the town of Horodło on 2 October 1413.
 The first act was signed by Władysław II Jagiełło, King of Poland, and Vytautas, Grand Duke of Lithuania.
 The second and third acts were composed by the Polish nobility (szlachta) and Lithuanian boyars respectively.
 The union amended the earlier Polish–Lithuanian unions of Krewo and Vilnius–Radom.
 Politically, Lithuania received more autonomy as, after the death of Vytautas, the Lithuanian nobles could choose another Grand Duke instead of passing the title to Władysław II Jagiełło or his heir.
 However, culturally, Lithuania and Poland grew closer.
 Lithuania adopted Polish institutions of castellans and voivodes. Catholic Lithuanian nobles and church officials were granted equal rights with the Polish nobles and clergy.
 Forty-seven selected Lithuanian nobles were adopted by Polish families and granted Polish coats of arm.
 Thus the union signified the beginnings of Polonization of Lithuanian culture and the rise of the Lithuanian nobility.
 It was one of the major steps towards the modernization and Europeanization of Lithuania.
John III Sobieski (Polish: "Jan III Sobieski" ; Lithuanian: "Jonas III Sobieskis" ; Latin: "Ioannes III Sobiscius" ; 17 August 1629 – 17 June 1696), was King of Poland and Grand Duke of Lithuania from 1674 until his death, and one of the most notable monarchs of the Polish–Lithuanian Commonwealth.
The Lithuanian Civil War of 1381–1384 was the first struggle for power between the cousins Jogaila, Grand Duke of Lithuania and later King of Poland, and Vytautas the Great.
 It began after Jogaila signed the Treaty of Dovydiškės with the Teutonic Knights which was aimed against his uncle Kęstutis, father of Vytautas.
 Kęstutis briefly seized power in the Grand Duchy, but was betrayed by adherents of Jogaila primarily from Vilnius.
 During negotiations for a truce Kęstutis and Vytautas were arrested and transported to the Kreva Castle.
 Kęstutis died there a week later but Vytautas managed to escape and then sought an alliance with the Teutonic Knights.
 Subsequently their joint forces raided Lithuanian lands.
 Eventually the cousins were reconciled as Jogaila needed internal stability in anticipation of negotiations with the Grand Duchy of Moscow and the Kingdom of Poland regarding the possible Christianization of Lithuania.
 The war did not settle the power struggle; it continued during the next Lithuanian Civil War (1389–1392) which was resolved by the signing of the Ostrów Agreement.
 After more than ten years of struggle, Vytautas finally became the Grand Duke of Lithuania and ruled the country for thirty-eight years.
Malcolm was the son of Robert Kennedy and Clementina Sobieska Stuart Kennedy (née Robertson), he was born on 23 October 1892 in Kew, Victoria.
Clementina of Austria (German: "Maria Clementina Franziska Josepha" 1 March 1798 – 3 September 1881) was an Archduchess of Austria and "Princess of Salerno" upon her marriage to Prince Leopold of Bourbon-Two Sicilies, Prince of Salerno.
The Lithuanian Civil War of 1389–92 was the second civil conflict between Jogaila, King of Poland and Grand Duke of Lithuania, and his cousin Vytautas.
 At issue was control of the Grand Duchy of Lithuania, then the largest state in Europe.
 Jogaila had been crowned King of Poland in 1386; he installed his brother Skirgaila as ruler of Lithuania.
 Skirgaila proved unpopular and Vytautas attempted to depose him.
 When his first attempt to take the capital city of Vilnius failed, Vytautas forged an alliance with the Teutonic Knights, their common enemy – just as both cousins had done during the Lithuanian Civil War between 1381 and 1384.
 Vytautas and the Knights unsuccessfully besieged Vilnius in 1390.
 Over the next two years it became clear that neither side could achieve a quick victory, and Jogaila proposed a compromise: Vytautas would become Grand Duke and Jogaila would remain Superior Duke.
 This proposal was formalized in the Ostrów Agreement of 1392, and Vytautas turned against the Knights.
 He went on to reign as Grand Duke of Lithuania for 38 years, and the cousins remained at peace.
Jogaila, later Władysław II Jagiełło (] ) (c. 1352/1362 – 1 June 1434) was the Grand Duke of Lithuania (1377–1434) and then the King of Poland (1386–1434), first alongside his wife Jadwiga until 1399, and then sole King of Poland.
 He ruled in Lithuania from 1377.
 Born a pagan, in 1386 he converted to Catholicism and was baptized as Władysław in Kraków, married the young Queen Jadwiga, and was crowned King of Poland as Władysław II Jagiełło.
 In 1387 he converted Lithuania to Christianity.
 His own reign in Poland started in 1399, upon the death of Queen Jadwiga, and lasted a further thirty-five years and laid the foundation for the centuries-long Polish–Lithuanian union.
 He was a member of the Jagiellonian dynasty in Poland that bears his name and was previously also known as the Gediminid dynasty in the Grand Duchy of Lithuania.
 The dynasty ruled both states until 1572, and became one of the most influential dynasties in late medieval and early modern Central and Eastern Europe.
 During his reign, the Polish-Lithuanian state was the largest state in the Christian world.
Sophia of Halshany or Sonka Olshanskaya (Belarusian: Соф'я Гальшанская, "Sofja Halšanskaja" ; Lithuanian: "Sofija Alšėniškė" ; Polish: "Zofia Holszańska" ;  1405 – September 21, 1461 in Kraków) was a Grand Duchy of Lithuania princess of Halshany.
 As the fourth and last wife of Jogaila, King of Poland and Supreme Duke of Lithuania, she was Queen consort of Poland (1422–1434).
 As the mother of Władysław III, King of Poland and Hungary, and Casimir IV, Grand Duke of Lithuania and King of Poland, she was the founder of the Jagiellon dynasty.
Maria Clementina Sobieska (in Polish Maria Klementyna Sobieska; 18 July 1702 – 18 January 1735) was a Polish noblewoman, the granddaughter of the Polish king John III Sobieski, the wife of James Francis Edward Stuart, Jacobite claimant to the British throne, and mother of Charles Edward Stuart and of Cardinal Henry Benedict Stuart

Question: What year did this grandfather Maria Clementina Sobieska become king of Poland and Grand Duke of Lithuania?
Answer: 1674