Hardy as he was, La Salle sometimes fell ill from the great exposures he endured. And more than once he was poisoned by some revengeful voyageur. It was not until the December following his discovery of the Mississippi's mouth that he realized his plan of fortifying the rock on the Illinois River. He and Tonty delighted in it, calling it Fort St. Louis of the Illinois. Storehouses and quarters for a garrison rose around its edges, protected by a palisade. A windlass was rigged to draw water from the river below. On the northeast corner of the rock a low earthwork remains to this day.
Around this natural castle the Indian tribes gathered to La Salle, as to a sovereign,—Miamis, Abenakis, and Shawanoes, from countries eastward, and the Illinois returned to spread over their beloved meadow. Instead of one town, many towns of log, or rush, or bark lodges could be seen from the summit of the Rock. Years afterwards the French still spoke of this fortress as Le Rocher. A little principality of twenty thousand inhabitants, strong enough to repel any attack of the Iroquois, thus helped to guard it. La Salle meant to supply his people with goods and give them a market for their furs. At this time he could almost see the success of his mighty enterprise assured; he could reasonably count on strengthening his stockades along the Mississippi, and on building near its mouth a city which would protect the entire west and give an outlet to the undeveloped wealth of the continent.
In the flush of his discovery and success La Salle went back to France, leaving Tonty in charge of the Rock and the gathering Indian nations, and laid his actual achievements before the king, asking for help. This was made necessary by the change in the colonial government, which had removed his friend Count Frontenac and left him at the mercy of enemies.
The king was not slow to see the capacity of this wonderful man, so shy of civilization that he lodged in a poor street, carrying with him the very breath of the wilderness. La Salle asked for two ships; the king gave him four; and many people and supplies were gathered to colonize and stock the west.
It was La Salle's intention to sail by way of the West Indies, cross the Gulf of Mexico, and enter the mouth of the Mississippi. But the Gulf of Mexico is rimmed with low marshy land, and he had never seen the mouth of the Mississippi from seaward. His unfamiliarity with the coast, or night, or fog cheated him of his destination, and the colony was landed four hundred miles west of it, in a place called Matagorda Bay, in Texas, which then belonged to the Spaniards. Although at the time of discovery he had taken the latitude of that exact spot where he set the post, he had been unable to determine the longitude; any lagoon might be an opening of the triple mouth he sought.
La Salle's brother, a priest, who sailed with him on this voyage, testified afterwards that the explorer died believing he was near the mouth of the Mississippi. Whatever may have been his thoughts, the undespairing Norman grappled with his troubles in the usual way. One of his vessels had been captured by the Spanish. Another had been wrecked in the bay by seamen who were willing to injure him. These contained supplies most needed for the colony. The third sailed away and left him; and his own little ship, a gift of the king for his use along the coast, was sunk by careless men while he was absent searching northward for the Mississippi.
Many of the colonists fell sick and died. Men turned sullen and tried to desert. Some went hunting and were never seen again. Indians, who dare not openly attack, skulked near and set the prairie on fire; and that was a sight of magnificence, the earth seeming to burn like a furnace, or, far as the eye could follow them, billows of flame rushing as across a fire sea. But La Salle was wise, and cut the grass close around his powder and camp.