Complex sentence: The siege of Krems in 1477 by Matthew Corvinus was one of the first times that cannon were effectively used to batter down a town wall and this incident seems to have resulted in many of the Austria town walls being strengthened or re-designed.
Split into simpler sentences: The siege of Krems in 1477 by Matthew Corvinus was one of the first times that cannon were effectively used to batter down a town wall. This incident seems to have resulted in many of the Austria town walls being strengthened or re-designed.