Blockade-running soon became almost as much an art as a trade, and there were some grumblers in this country who made it a ground of complaint that no English officers had been sent to observe the new development in this branch of naval warfare. The most ingenious expedients were resorted to on both sides. A system of signalling by means of blue lights and rockets was in many cases established between the forts and their friends in the offing. The steamer _Hansa_ ran into Wilmington while Fort Fisher was being bombarded, and prevented pursuit by boldly sailing close past the powder-ship, which shortly afterwards blew up. Occasionally, a furious cannonade was begun from some adjacent fort, so as to draw off the blockading squadron, and leave the entrance free, if only for a few hours. The blockaders had their tricks too. Sometimes heavy smoke was seen rising as from a ship on fire; but when the blockade-runner steered to render help, she found out too late that the supposed burning vessel was a Federal cruiser, which had resorted to this device in order to bring the swifter craft within range of her guns. One dark rainy night the _Petrel_ ran out of Charleston, and shortly afterwards fell in with what appeared to be a large merchant vessel. Hoping to crown a successful run with the capture of a valuable prize, she gave chase, and fired a shot to bring the stranger to. The reply was a single broadside, so well directed that there was no need for another. The supposed merchantman was the frigate _St Lawrence_. A favourite ruse of the privateer _Jeff Davis_ was to hoist the French flag of distress, and when a ship bore down in response to this appeal, she would, under pretence of handing in a letter, send aboard a boat’s crew armed to the teeth.