Upon Isle Royale there was a French post of some strength, called Fort Levi, which Amherst determined to subdue, partly because he was unwilling to leave an enemy in his rear, but principally because among the little garrison were several men well skilled in the dangerous navigation of the St. Lawrence, whose services might prove of great value to the expedition; accordingly, the fort was completely invested by the 20th. On the 23d the British batteries were in readiness, and the armed vessels placed in a favorable position, while a detachment of grenadiers with scaling-ladders were told off to storm the works. A cannonade was opened upon the fort; but the gallant little garrison returned the fire with such spirit, that one of the British vessels which had got aground was obliged to strike her colors, and was abandoned by her crew. Amherst, astonished at this vigorous resistance, deferred his contemplated assault to another day. The delay proved fortunate in preventing further bloodshed; for M. Pouchot, the French commandant, seeing that there was no hope of a successful defense, surrendered at discretion on the 25th. When the fort was delivered up, a circumstance occurred which reflects far more honor upon Englishmen than the triumph of their arms. Johnson's Indians had secretly determined to seize their opportunity of vengeance, and to massacre the gallant band of Frenchmen as soon as they gained admission within the works. Happily, Amherst was made aware of this atrocious scheme. He immediately gave orders to Sir William to dissuade the savages, if possible, from their intention; at the same time, he promised them all the stores which might be found in the fort, and warned them that if they persisted he would restrain them by force. The Indians sullenly submitted and returned to their camp, but they bitterly resented the interference, and Johnson informed the general that they would probably quit the army in anger. Amherst answered, "Although I wish to retain their friendship, I will not purchase it at the expense of countenancing barbarity; and tell them that, if they commit any acts of cruelty on their return home from the army, I will assuredly chastise them." Amherst lost his Indians, but he preserved his honor. Nearly all abandoned him; they did not, however, dare to perpetrate any violence on their way home.