It being useless to attempt further disguise, he cleared for action and offered the _Minerva_ battle.

The captain, however, deemed it his duty to remain with his convoy, and continued his course to Quebec, while Porter headed southward, afterward restoring his prize to its owners for a liberal ransom.
Captain Porter had become so clever in disguising his vessel as a merchantman that some days later he lured the British 16-gun ship-sloop _Alert_ to attack him.

In the space of eight minutes the _Alert_ was so helplessly crippled that her captain surrendered.

The _Essex_ did not suffer the slightest injury and no men were killed on either vessel.
The _Essex_ had now five hundred prisoners aboard, and they formed an element of serious danger, for they began plotting among themselves to capture the ship from the Americans and turn her over to the enemy.
Captain Porter was a severe disciplinarian, and one of his practices was to have the alarm of fire sounded at all hours of the day or night, that his crew might be taught the successful way of fighting the ever-present danger.

To make such training perfect, he occasionally started a fire in the hatches.
The leader in the conspiracy to seize the ship fixed upon a night to make the attempt, and his friends were on the alert to join him the moment he gave the signal.