 Complete the following phrase:  The further extension of the Moscow dominion was facilitated by the death of Casimir IV in 1492, when Poland and Lithuania once again parted company. The throne of Lithuania was now occupied by Casimirs son Alexander, a weak and lethargic prince so incapable of defending his possessions against the persistent attacks of the Muscovites that he attempted to save them by a matrimonial compact, wedding Helena, Ivans daughter. But the clear determination of Ivan to appropriate as much of Lithuania as possible finally compelled Alexander to take up arms against his father-in-law in 1499. The Lithuanians were routed at the 