Complex sentence: However, by 1623 it was under assault once more, when it was besieged by Sir Robert Gordon during his feud with George Sinclair, 5th Earl of Caithness, but the Sinclairs surrendered the castle before any assault took place.
Split into simpler sentences: However, by 1623 it was under assault once more, when it was besieged by Sir Robert Gordon during his feud with George Sinclair, 5th Earl of Caithness. The Sinclairs surrendered the castle before any assault took place.