In reply to this unexpected attack Tenskwatawa assured his followers that he would give them convincing proof of his being the true messenger of the Great Spirit, and he boldly predicted that on a certain day he would draw a veil of darkness over the sun. Many Indians assembled to witness the test of his supernatural power. If it succeeded, it would establish his position beyond doubt; if it failed, the faith of his followers would be sadly shaken. Scoffers pointed to the brightness of the summer sun, and openly questioned the power of the Prophet to dim its rays. Believers furtively watched the entrance of the Prophet's lodge, which was decorated with strange symbols. From it at the time appointed the familiar form of the one-eyed wizard emerged, clad in his prophet's robe with outspread raven's wings. At his appearance the noonday brilliance of the sun began to wane. Sudden silence fell upon the awestruck throng, and faces took on a look of fear as the darkness deepened about them. The Prophet's voice thrilled through the gloom. 'Did I not prophesy truly? Behold, darkness has shrouded the sun.' The apparent miracle convinced many unbelievers and established the influence of Tenskwatawa more strongly than ever. The Indians were completely deceived. The achievement had, of course, a very simple explanation: the Prophet had overheard some white missionaries predicting an eclipse of the sun, and had used this information very adroitly for his purpose. In April 1807 some four hundred redskins had gathered near Greenville, ready to do the Prophet's bidding. Tenskwatawa and Tecumseh were invited by Captain Wells, the Indian agent at Fort Wayne, to visit the fort with a few chiefs, to learn the news contained in a recent letter from the president of the Seventeen Fires. [Footnote: The United States. Four new states had been added to the original thirteen, making, in Indian terms, seventeen council fires.] Tecumseh peremptorily commanded the messenger to 'go back to Fort Wayne and tell Captain Wells that my fire is kindled on the spot appointed by the Great Spirit above, and, if he has anything to communicate to me, he must come here; I shall expect him in six days from this time.' At the time appointed the messenger returned, bearing a copy of a letter from the United States government, in which Tecumseh and his followers were charged with still occupying land that had passed out of their possession by the Treaty of Greenville. Tecumseh vented his feelings in vehement speech.