Just off Charleston's harbor, Blackbeard's fleet was preying on the many merchant ships leaving the bustling port. In addition to the plundering of the cargo and passengers' belongings, Blackbeard added a new tactic: hostages. His ships soon held a number (counts vary from 5 to 25) of influential South Carolinians as captives.
Sailing closer to the mouth of Charleston Harbor, he sent a dingy ashore with his ransom demands. What Blackbeard demanded was not silver or gold -- but medicine to treat his men. He had laid seige to a wealthy port city and was in position to demand a huge sum, yet he was demanding medical stores from Charleston. This causes many to speculate that Blackbeard himself was ill. No one knows how many of his crew were ill, but the numbers must have been great to risk such a confrontation.
Blackbeard pressured Charleston by advancing his fleet of heavily-armed ships into the harbor. The Queen Anne's Revenge, his flagship, carried 40 guns of her own. If he chose to sack the city, his crew now numbered well over 300 men.
The city wisely chose to meet Blackbeard's ransom, delivering a chest of medicines. Without pressing his advantage --or firing a shot-- the pirate released his hostages and withdrew.