The first administration of Frontenac will always be associated with the intrepid enterprises of the great western explorers, Jolliet, La Salle, Du Lhut, Nicolas Perrot, and others. To Jolliet is reasonably assigned the first discovery of the Mississippi. Starting from Green Bay, or, as it was then called, Baie des Puants, on the west shore of Lake Michigan, in company with the Jesuit father, Marquette, he worked his way to the Wisconsin River, which he followed to its junction with the Mississippi; and then descended the latter river till he reached latitude 33°, or about as far as the northern boundary of the present state of Louisiana. Fear of falling into the hands of the Spaniards, who, as he was informed by the Indians, had settlements not far to the south, caused him to retrace his steps. When he was just completing his return journey, his canoe upset close to Montreal, and all his papers were lost, including the notes he had made of his observations, and a map of the region through which he had passed. He himself narrowly escaped with his life--the laws of nature were in fact suspended, as he gravely declares, in his behalf--but a young savage whom he was bringing from the country of the Illinois was drowned.[22] He reached Quebec in the month of August 1674, and the thrilling account which he gave of his adventures produced a strong impression on the mind of the governor. Nevertheless when, two years later, he asked permission to go with twenty men to make further explorations in the same direction, Colbert refused his request. A possible explanation is that his previous journey with Père Marquette had established relations which Frontenac did not quite approve between him and the Jesuits in the western country, who had lost no time in pushing their missions towards the south. However this may have been, Frontenac had his eye at this very time upon a man who seemed to him much better suited to be an agent of his policy.
It has already been mentioned that Robert Cavelier de la Salle obtained from the king in the year 1675 a grant of the fort erected by Frontenac at Cataraqui. The conditions of the grant were that he was to reimburse the cost of construction, estimated at ten thousand livres; keep it in good repair; maintain a sufficient garrison; employ twenty men for two years in clearing the land conceded to him in the neighbourhood; provide a priest or friar to perform divine service and administer the sacraments; form villages of Indians and French; and have all his lands cleared and improved within twenty years. On these terms he was to have four square leagues of land, that is to say, eight leagues in length along the river and lake front, east and west of the fort, by half a league in depth, together with the islands opposite. But what was of most value in a pecuniary sense, and what he depended on to compensate his outlay, was the right of hunting and fishing in the neighbouring region, and of trading with the Indians. To what extent La Salle actually developed the property thus conceded to him is a matter of dispute. The Abbé Faillon, who perhaps has some little animus against him, says that he did nothing worth mentioning towards establishing such a colony as the king intended. The king, on the other hand, when granting La Salle authority to undertake explorations in the direction of the Mississippi speaks approvingly of the work he had done on his concession. The information may have been derived from La Salle himself, who went to France in the autumn of 1677 to obtain sanction for his proposed expedition; but it is hardly likely that he would lay altogether false information before the minister for submission to the king. It seems to be certain that he did at least put the fort in a good condition of defence. He pulled down the old one, which consisted merely of a wooden palisade banked up with earth and having a circumference of one hundred and twenty yards, and replaced it by one having a circumference of seven hundred and twenty yards, and protected by four stone bastions.