Seimas of the Grand Duchy of Lithuania

Seimas (Sejm, Sojm, Belarusian: Сойм) was an early parliament in the Grand Duchy of Lithuania. It was active from 1445 to 1569, when it was officially abolished by the Union of Lublin. The Seimas was an irregular gathering of the Lithuanian nobility, called as needed by the Grand Duke or during an interregnum by the Lithuanian Council of Lords (an early government). The meetings would usually last one or two weeks. Seimas gradually evolved from a meeting of the most powerful magnates to a full legislative institution representing all of the nobility. The Seimas was not the main political player as it was overshadowed by the Council of Lords. The Union of Lublin created a new state, the Polish–Lithuanian Commonwealth, and joined the Seimas of Lithuania with Sejm of Poland into one Sejm of the Polish–Lithuanian Commonwealth. However, the Seimas continued to convene under the name of Lithuanian Convocation. In total there were 40 Seimas and 37 Convocations.

The first traces of large nobility meetings can be found in the Treaty of Salynas of 1398 and the Union of Horodło of 1413. It is considered that the first Seimas met in Hrodna in 1445 during talks between Casimir IV Jagiellon and the Council of Lords. Soon influence of the nobility grew as Casimir's privileges released veldamas, dependent peasants, from their taxes to the state. That meant a significant increase in nobility's revenue. As the Muscovite–Lithuanian Wars raged the country almost continuously between 1492 and 1582, the Grand Duke needed more tax revenues to finance the army and had to call the Seimas more frequently. In exchange for cooperation, the nobility demanded various privileges, including strengthening of the Seimas.

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