Complex sentence: An attempt on 17 December to bombard the "San Miguel" by the Spanish and French with mortars failed causing only minimal damage but by this time the powder magazine had been removed or thrown overboard Drinkwater pg.157.
Split into simpler sentences: An attempt on 17 December to bombard the "San Miguel" by the Spanish and French with mortars failed causing only minimal damage. By this time the powder magazine had been removed or thrown overboard Drinkwater pg.157.