Eager to engage and defeat one of the American frigates that had already scored a number of victories over the Royal Navy in single-ship confrontations, Broke prepared a challenge. had already slipped out of the harbour under the cover of fog and had evaded the British. "Constitution" was undergoing extensive repairs and alterations and would not be ready for sea in the foreseeable future. However, "Chesapeake" appeared to be ready to put to sea. Consequently, Broke decided to challenge "Chesapeake", which had been refitting in Boston harbour under the command of Captain James Lawrence, offering single ship-to-ship combat. Whilst patrolling offshore, "Shannon" had intercepted and captured a number of American ships attempting to reach the harbour. After sending two of them off to Halifax, he found that his crew was being dangerously reduced. Broke therefore resorted to burning the rest of the prizes in order to conserve his highly trained crew in anticipation of the battle with "Chesapeake". The boats from the burnt prizes were sent into Boston, carrying Broke's oral invitation to Lawrence to come out and engage him. Broke had already sent "Tenedos" away in the hope that the more favourable odds would entice the Americans out, but eventually began to despair that "Chesapeake" would ever come out of the harbour. He finally decided to send a written challenge. In this he was copying his adversary. Lawrence had earlier in the war, when captain of the sloop of war , sent a written invitation to the captain of the British sloop of war to a single-ship contest. Lawrence's offer had been declined.