of wood surrounded by a wooden stockade consisting of sharpened poles, was completed within six days. La Salle administered the fort and built storage buildings and dwellings, brought in domestic animals and ensured some land outside the fort was cultivated with the aim of attracting settlers. The fort was sited to protect a small sheltered bay (the "cannotage") that the French could use as a harbour for large lake-going boats. Unlike the Ottawa River fur trade route into the interior, which was only accessible by canoes, larger vessels could easily navigate the lower lakes. The cost of transporting goods such as furs, trade items, and supplies through at least the lower Great Lakes would be reduced. La Salle was granted seigneurial privileges in the vicinity of the fort. In return for these privileges, La Salle was obliged to reimburse Frontenac for expenses related to building the fort, keep 20 workers onsite for two years, and maintain the fort. In 1675, La Salle rebuilt the structure. Stone bastions and a stone wall were constructed to strengthen the fort and much of the wooden pallisade was rebuilt. He was also required to attract settlers and meet their spiritual needs by building a chapel and establishing a mission with one or two Recollet priests. A description of the fort written in the 17th century mentions that: La Salle used Fort Frontenac as a convenient base for his explorations into the interior of North America. Iroquois siege and reconstruction Fur trade rivalries continued to cause friction between the French and the Iroquois in the 1680s. The French began a campaign against the Iroquois to resolve the Iroquois threat, beginning with Governor Antoine Lefèbvre de La Barre's unsuccessful expedition to Fort Frontenac and into Seneca territory south of Lake Ontario in 1684. In 1687 La Barre's successor, the Marquis de Denonville, gathered an army to travel into the Seneca territory. To quell suspicion about his motives, Denonville let on that he was merely travelling to a peace council at Fort Frontenac. As Denonville and his army moved up the St. Lawrence toward the fort, several Iroquois, many of whom were friendly to the French, including women and children and some prominent leaders, were captured and imprisoned at Fort Frontenac by intendant de Champigny ostensibly to prevent them from revealing Denonville's troops' location. Some were held hostage and sent to Montreal in the event that any