In addition, several of the merchantmen were heavily armed.
Captain Porter's next act was still more audacious.

He glided forward among the fleet and hailed the captain of a second vessel, but the latter became suspicious, and was on the point of signalling to the escort the appearance of a stranger among them, when Porter thrust out the muzzles of twenty cannon and warned him that if he failed to keep perfect silence and follow in his wake he would blow him out of the water.

The English captain obeyed, and Porter extricated his prize with such astonishing skill that not a vessel took the alarm.

When a safe point was reached, Porter found that his prize was a brig with about two hundred British soldiers on board.
Having succeeded so well, Porter again returned to the fleet for another capture.

But by this time day was breaking and the character of his vessel was discovered.