The novelty of Poland believed that strong country would never fall apart. However, what strengthened the medieval country, has been later on one of the reasons of the partitions in 18th century. The union of Poland and Lithuania decentralized the ruling power of the country. Rich families started to have more and more influence over the politics and acted with the aim of getting even more power (not realizing that at the same time it led to long-term crisis).
The worst invention of 17th century Polish-Lithuanian Commonwealth was the policy of parliamentary procedure called ‘Liberum Veto’. A single member of parliament could strike any act that he perceived as created against his own state and unanimous consent was required when voting for any measures. Since then all the reforms could be stopped by one single selfish or bribed citizen. The country was becoming weaker and weaker.
At the same time the neighbors of Polish-Lithuanian Commonwealth grew in power. In 1730 the three countries (namely Russia, Prussia and Austria) signed secret agreement (called later in Poland ‘Alliance of the Three Black Eagles’) that would designate the territories of their influence. The same three countries would soon divide the lands of Poland and Lithuania and make it dependant on them and their rule.
The first partition of the country took place in 1772. Troops of the three occupants entered the lands of Poland and occupied the territories agreed between themselves. The connected with the first partition did not take into accounts further division of Poland (and at the same time Lithuania). The occupants tried even to prove that the act of partition is signed with the aim of protecting the big country from internal and external conflicts with the help of Austria, Prussia and Russia. The act of 1772 partition was signed by Polish parliament in 1773 (with the protest of few of its members) and with the consent of Stanislaw August Poniatowski king, whose personal agreement brought him material goods.
Second partition took place in 1793 (and was done by only 2 occupants – Prussia and Russia). Another events that cause the Poles fighting between themselves was May Constitution of 1791. Pro-Russian magnates believed that Russia would help them to restore their Golden Liberty. In the result of second partition Poland lost two third of its Population of 1772. Increasing support for reforms caused Kosciuszko Uprising but that not stop the occupants from the third partition that ceased the existence of Commonwealth for years (in 1795).
Although there were attempts to resurrect the country, it was only performed in a smaller frame in 1807 when with agreement of Napoleon so called Duchy of Warsaw was set up. After he was defeated, the Congress of Vienna in 1815 decided to replace it with Kingdom of Poland. But the Poles would still long for full independence. However, their further fights (like insurrection of 1831 and 1863) caused to abolishing the autonomy of Kingdom. It was, however, not until 1918 that the Poles could rejoice their freedom.