Agna of Šiauliai was born circa 1242 in Šiauliai, Lithuania and died circa 1263 Vilnius, Lithuania of unspecified causes. She married Daumantas of Pskov (c1240-1299) . She married Mindaugas (c1200-1263) .
Very little is known about her. She was married to Daumantas, at that time was Duke of Nalšia, a northern province of the Grand Duchy of Lithuania. The exact location of the Duchy is disputed, but, according to some accounts, the main city of the principality was Kreva. According to some accounts they had a young son called Polyushem, though there is no further information about him.
Though they differ in the details, according to the Galician–Volhynian Chronicle and also to the Bychowiec Chronicle, after Queen Morta's death, king Mindaugas made arrangements for her funeral. Agna attended her sister's funeral, but for some reason, her husband Daumantas was not present.
Mindaugas claimed that the Queen Morta's last wish was that he marry her sister, so that she could take care of her young sons, though this reason is difficult to accept, as they were about 12-15 years old. According to other accounts, Mindaugas simply fell in love with his young sister in law, who was about 20 years old while he was over 60. Apparently, Agna did not submit willingly to Mindaugas' demands and she was kept prisoner by force. There are no information that Mindaugas formally married her. She seems to have fallen ill and to have never recovered, dying after a short time.
According to legend, Daumantas called to Kreva his three brothers as well as Agna's father. They were however compelled to admit that their forces were insufficient for an open fight with Mindaugas. However they were able to join forces with Treniota a nephew of Mindaugas, who was in conflict with the king and was seeking to replace him on the Lithuanian throne. Taking advantage of a time when the king had sent his army to fight the Principality of Bryansk, Treniota and Daumantas were able to enter the king's castle and to kill him and his two young sons. According to a late medieval tradition, the assassination took place in Aglona. There are no accounts that Daumantas was able to liberate his wife, which seems to confirm the assumption that she died in captivity before the attack.
Mindaugas' elder son, Vaišvilkas had taken the vows and had become a monk. During his father's assassination he was in the Assumption Monastery in Leshcha near Pinsk which he is assumed to have founded. Despite his monastic status, Vaišvilkas took up arms to revenge his father. Daumantas was forced to leave his fief in Lithuania and the seek refuge in Pskov.
- ^ Jakštas, Juozas (1969). "Lithuania to World War I". In Albertas Gerutis (ed.). Lithuania: 700 Years. translated by Algirdas Budreckis. New York: Manyland Books. pp. 43–58. LCC 75-80057.
- ^ (Lithuanian) Ivinskis, Zenonas (1978). Lietuvos istorija iki Vytauto Didžiojo mirties. Rome: Lietuvių katalikų mokslo akademija. p. 195. LCC 79346776.