in 1792 he negotiated in vain with a saxon delegation on the introduction of the hereditary transmission of the polish crown to the king of saxony. małachowski was stricter than patriot opponents of the russian party, whose main proponents scored his brother hyacinth małachowski. during the russo-polish war of 1792, he provided substantial funds and large quantities of food for the polish troops available from his own resources. but since he could not prevent the pro-russian targowica confederation, he fled abroad. he did not take part in the kościuszko uprising of 1794. in 1799, he was nevertheless arrested in warsaw and imprisoned for a year in kraków as a state prisoner, being accused of responsibility for a meeting of the polish sejm in milan. after the founding of the grand duchy of warsaw in 1807, he was first chairman of a provisional government commission and soon became president of the senate.