Complex sentence: After this initial invasion of Bohemia, the war deteriorated to a series of mostly border raids and was not concluded until 950, when Otto besieged a castle owned by Boleslaus' son.
Split into simpler sentences: After this initial large-scale invasion of Bohemia, hostilities were pursued in a series of mostly border raids. The war was not concluded until 950, when Otto besieged a castle owned by Boleslaus' son.