Gediminid line. The cooperation between Lithuania and Tver lasted well into the 15th century. Aldona (baptized as Ona or Anna; her pagan name is known only from the writings of the 16th century chronicler Maciej Stryjkowski) married Casimir III of Poland, son of Władysław I of Poland, when he was 15 or 16 years old. The marriage took place on either 30 April or 16 October 1325, and was a purely political maneuver to strengthen the Polish–Lithuanian coalition against the Teutonic Knights (an alliance foreshadowing the Union of Krewo in 1385 and the Union of Lublin in 1569, with the latter resulting in a stable and powerful new state, the Polish–Lithuanian Commonwealth). This preliminary coalition was short-lived, collapsing in about 1330, but there is no evidence of military conflict between Poland and Lithuania while Aldona was alive. The marriage into the Lithuanian dynasty that had ruled since about 1289 might have lent legitimacy to the rule of Władysław I of the Piast dynasty, who was crowned in 1320, replacing the Přemyslid dynasty. But Aldona died unexpectedly at the end of May 1339 and was buried in Kraków. Aldona had two daughters: Cunigunde (d. 1357) married Louis VI the Roman, the son of Louis IV, Holy Roman Emperor, and Elisabeth (d. 1361) married Duke Bogislaw V of Pomerania, an area in modern-day Germany and Poland. Elisabeth's daughter, Elizabeth of Pomerania, was the fourth wife of Charles IV, Holy Roman Emperor. Gediminas' daughter Elzbieta married Wacław of Płock, one of the dukes of Masovia in modern-day eastern Poland. Her second name is recorded in writings by Maciej Stryjkowski as Danmila and Teodor Narbutt as Damila. It has been suggested these names are misread versions of Danutė, a name derived from Daniel. Another interpretation is that historians confused Danutė of Lithuania, daughter of Kęstutis, with Elzbieta. As an alliance, the marriage was significant because passages to and from western Europe had to go through Masovia; it can be seen as an attempt to revive Grand Duke Traidenis' and his daughter Gaudemunda's link with Masovia in the 1270s. The marriage's importance is attested by Elzbieta's dowry: 720 Kraków silver marks and nine marks of gold – three times more than an ordinary recorded dowry of the time. This marriage probably took place about 1316, when Gediminas supported Wacław during a civil war in the divided Duchy of Masovia. After Wacław's death in 1336, Elzbieta