This belt told him to strike in his own interest and in the interest of the French.  He closed his speech by saying that he had sent belts to the Chippewas of Saginaw and the Ottawas of Michilimackinac and of the river La Tranche (the Thames).  Seeing that his words were greeted with grunts and shouts of approval and that the assembled warriors were with him to a man, Pontiac revealed a plan he had formed to seize the fort and slaughter the garrison.  He and some fifty chiefs and warriors would wait on Gladwyn on the pretence of discussing matters of importance.  Each one would carry beneath his blanket a gun, with the barrel cut short to permit of concealment.  Warriors and even women were to enter the fort as if on a friendly visit and take up positions of advantage in the streets, in readiness to strike with tomahawks, knives, and guns, all which they were to have concealed beneath their blankets.  At the council Pontiac was to address Gladwyn and, in pretended friendship, hand him a wampum belt.  If it were wise to strike, he would on presenting the belt hold its reverse side towards Gladwyn.  This was to be the signal for attack.  Instantly blankets were to be thrown aside and the officers were to be shot down.  At the sound of firing in the council-room the Indians in the streets were to fall on the garrison and every British soldier was to be slain, care being taken that no Frenchman suffered.  The plan, by its treachery, and by its possibilities of slaughter and plunder, appealed to the savages; and they dispersed to make preparations for the morning of the 7th, the day chosen for carrying out the murderous scheme.

The plot was difficult to conceal.  The aid of French blacksmiths had to be sought to shorten the guns.  Moreover, the British garrison had some friends among the Indians.  Scarcely had the plot been matured when it was discussed among the French, and on the day before the intended massacre it was revealed to Gladwyn.  His informant is not certainly known.  A Chippewa maiden, an old squaw, several Frenchmen, and an Ottawa named Mahiganne have been mentioned.  It is possible that Gladwyn had it from a number of sources, but most likely from Mahiganne.  The ‘Pontiac Manuscript,’ probably the work of Robert Navarre, the keeper of the notarial records of the settlement, distinctly states that Mahiganne revealed the details of the plot with the request that Gladwyn should not divulge his name; for, should Pontiac learn, the informer would surely be put to death.  This would account for the fact that Gladwyn, even in his report of the affair to Amherst, gives no hint as to the person who told him.

Gladwyn at once made preparations to receive Pontiac and his chiefs.  On the night of the 6th instructions were given to the soldiers and the traders within the fort to make preparations to resist an attack, and the guards were doubled.  As the sentries peered out into the darkness occasional yells and whoops and the beating of drums reached their ears, telling of the war-dance that was being performed in the Indian villages to hearten the warriors for the slaughter.