Complex sentence: He was in some sort a Scottish "Drake", part naval officer, part pirate, and had unpleasantly surprised the English on an element where Scotland had hitherto counted for very little, either in peace and war.
Split into simpler sentences: He was in some way a Scottish "Drake", part naval officer, part pirate. He had unpleasantly surprised the English on an element where Scotland had hitherto counted for very little, either in peace and war.