King Uzziah was one of the most effective kings of Judah, and in his early years he also enjoyed good relations with the Jerusalem priesthood, which had been instrumental in Judean royal politics for several generations. He conquered the Philistines, subdued the Ammonites and Arabs, and even managed to stay away from conflict with the northern Kingdom of Israel, making Judah probably as powerful as it ever had been.
Uzziah's downfall came when he made the mistake of trying to usurp one of the priestly functions by burning incense in the Temple of Jerusalem. While it is easy to adopt the biblical view that this was a serious sin, we cannot say with certainty that the priests were right to so absolutely condemn him for it, or even that his supposed leprosy was not a preexisting skin disease used by the priests to banish him. During this time, we must recall, the priests of Jerusalem had recently been involved in assassinations and other palace intrigues and were certainly not beyond using their priestly prerogatives to place a more compliant ruler on the throne in the person of Uzziah's 16 year old son Jotham.
Whatever the truth of the matter, it is interesting to speculate as to whether, if he had been able to remain in control, Uzziah could have maintained Judah's strength and independence. Damascus was a serious threat to the northeast, and looming on the horizon was the increasing strength of the Assyrian Empire. However, if Judah had been able to forge an alliance and ultimately reunion with the northern Kingdom of Israel, it may have been able to withstand these threats. Losing the internal support of the priesthood weakened Uzziah's position, and it would not be long until Israel and Judah were fighting again. The northern kingdom would be destroyed by Assyria in 722 B.C.E., leaving Judah alone against its increasingly hostile neighbors, ultimately leading to the Babylonian Exile of 586 B.C.E.