Complex sentence: In 1578 Kornput had provided vital strategic assistance to Lalaing (before his betrayal) during the siege of Deventer, subsequently the city was forced to surrender and came into States hands.
Split into simpler sentences: In 1578 Kornput had provided vital strategic assistance to Lalaing (before his betrayal) during the siege of Deventer. Subsequently the city was forced to surrender and came into States hands.