In Federalist No. 22, Hamilton writes, "And in Sweden the parties were alternately bought by France and England in so barefaced and notorious a manner that it excited universal disgust in the nation, and was a principal cause that the most limited monarch in Europe, in a single day, without tumult, violence, or opposition, became one of the most absolute and uncontrolled." What is he talking about?
There have been 2 periods of absolute monarchy in the Kingdom of Sweden, with the first one being instituted by Charles XI and passed on to his son - Charles XII. The path towards Carolean absolute monarchy was gradually implemented during several Riksdag (national legislature similar to estates general) during the 17th century. It ended with the death of Charles XII in 1718. After this followed what is referred as the Age of Liberty, a period of relative political freedom and parliamentary governance. Relative is important since it was instituted in contrast to the absolute monarchy of Charles XII and his predecessor. It featured two main parties, called Hattarna and Mössorna that vied for political influence and main split point were on issues of foreign policy of the crumbling Swedish Empire. The age of liberty ended in 1772 by the coup d'etat of the then reigning king Gustav III. The coup was bloodless but put an effective end to the Age of Liberty by re-instituting the absolute monarchy in the Kingdom of Sweden, often referred to as the Gustavian era.
The Swedish monarchy was not significantly limited prior to the Carolean absolute monarchy. The bloodless coup and lack of resistance to the new monarchy of the Gustavian Era and the sudden change from relative political freedom to absolute monarchy makes it pretty clear that Hamilton references Gustav III coup of 1772.
Edit. Corrected the English spelling of Karolinska - Carolean - and corrected year for the first mention of the coup.