The years 1764-8 form a rare unity in Polish history, distinguished by an unprecedented attempt at constitutional and economic reform on a scale not to be repeated for another two decades. The fragile nature of the reforms which accompanied the election, in September 1764, of King Stanislaw August Poniatowski (1764-95) was revealed as early as autumn 1766, when internal opponents, supported by Russia and, to a lesser degree, Prussia, imposed the first serious checks on the reformers and then proceeded to try to secure their total defeat. The tensions between reformers and conservatives, compounded by large-scale Russian military and diplomatic intervention, were to plunge Poland into ungovernability and civil war by March 1768 and to drag it inexorably towards the First Partition.