Beginning in 1609, the League engaged in the Beaver Wars with the French and their Iroquoian-speaking Huron allies. They also put great pressure on the Algonquian peoples of the Atlantic coast and what is now the boreal Canadian Shield region of Canada and not infrequently fought the English colonies as well. During the seventeenth century, they were said to have exterminated the Neutral Nation. and Erie Tribe to the west. The wars were a way to control the lucrative fur trade, although additional reasons are often given for these wars.
In 1628, the Mohawks defeated the Mahicans to gain a monopoly in the fur trade with the Dutch at Fort Orange, New Netherland. The Mohawks would not allow Canadian Indians to trade with the Dutch. In 1645, a tentative peace was forged between the Iroquois and the Hurons, Algonquins and French. In 1646, Jesuit missionaries at Sainte-Marie among the Hurons went as envoys to the Mohawk lands to protect the precarious peace of the time. However, Mohawk attitudes toward the peace soured during the men’s journey. They were attacked by a Mohawk party en route. Taken to the village of Ossernenon (Auriesville, N.Y.), the moderate Turtle and Wolf clans decreed setting the priests free. Angered by this, the more hawkish Bear clan killed Jean de Lalande and Isaac Jogues on October 18, 1646. The two French priests were later commemorated as among the eight North American Martyrs. In 1649 during the Beaver Wars, the Iroquois used recently purchased Dutch guns to attack the Hurons. From 1651 to 1652, the Iroquois attacked the Susquehannocks without success.
In the early seventeenth century, the Iroquois were at the height of their power, with a population of about twelve thousand people. In 1654, they invited the French to establish a trading and missionary settlement at Onondaga (present-day New York state). The following year, the Mohawk attacked and expelled the French from this trading post, possibly because of the sudden death of 500 Indians from an epidemic of smallpox, a European infectious disease to which they had no immunity.
From 1658 to 1663, the Iroquois were at war with the Susquehannock and their Delaware and Province of Maryland allies. In 1663, a large Iroquois invasion force was defeated at the Susquehannock main fort. In 1663, the Iroquois were at war with the Sokoki tribe of the upper Connecticut River. Smallpox struck again; through the effects of disease, famine, and war, the Iroquois were threatened by extermination. In 1664, an Oneida party struck at allies of the Susquehannock on Chesapeake Bay.
In 1664, the French sent the Carignan regiment to New France under Marquis de Tracy with the orders “to carry war even to their firesides in order totally to exterminate them”. Out of fear, the Iroquois signed a peace treaty with the French. In 1666, the French invaded Iroquois territory. The Iroquois avoided battle; the French burned their villages.
Around 1670, the Iroquois drove the Siouan Mannahoac tribe out of the northern Virginia Piedmont region. They began to claim ownership of it by right of conquest. In 1672, the Iroquois were defeated by a war party of Susquehannock. The Iroquois appealed to the French for support. They asked Governor Frontenac to assist them against the Susquehannock because “it would be a shame for him to allow his children to be crushed, as they saw themselves to be… they not having the means of going to attack their fort, which was very strong, nor even of defending themselves if the others came to attack them in their villages.”
Some old histories state that the Iroquois defeated the Susquehannock during this time period. As no record of a defeat has been found, historians have concluded that no defeat occurred. In 1677, the Iroquois adopted the majority of the Susquehannock into their nation.
By 1677, the Iroquois formed an alliance with the English through an agreement known as the Covenant Chain. Together, they battled the French to a standstill who were allied with the Huron. These Iroquoian people had been a traditional historic foe of the Confederacy. The Iroquois colonized the northern shore of Lake Ontario and sent raiding parties westward all the way to Illinois Country. The tribes of Illinois were eventually defeated, not by the Iroquois, but rather by the Potawatomis. In 1684, the Iroquois invaded Virginian and Illinois territory again, and unsuccessfully attacked the French fort at St. Louis. Later that year, the Virginia Colony agreed at Albany to recognize the Iroquois’ right to use the North-South path running east of the Blue Ridge (later the Old Carolina Road), provided they did not intrude on the English settlements east of the fall line.
In 1679, the Susquehannock, with Iroquois help, attacked Maryland’s Piscataway and Mattawoman allies. Peace was not reached until 1685.
With support from the French, the Algonquian nations drove the Iroquois out of the territories north of Lake Erie and west of present-day Cleveland, which had been conquered during the Beaver Wars.
Jacques-Rene de Brisay de Denonville, Marquis de Denonville, Governor of New France from 1685 to 1689, set out with a well-organized force to Fort Frontenac. There they met with the 50 hereditary sachems of the Iroquois Confederation from the Onondaga council fire, who came under a flag of truce. Denonville recaptured the fort for New France and seized, chained, and shipped the 50 Iroquois Chiefs to Marseilles, France to be used as galley slaves. He then ravaged the land of the Seneca. The destruction of the Seneca land infuriated the Iroquois Confederation.
On August 4, 1689 they burned Lachine, a small town adjacent to Montreal, to the ground. Fifteen hundred Iroquois warriors had been harassing Montreal defences for many months prior to that. They finally exhausted and defeated Denonville and his forces. His tenure was followed by the return of Frontenac, who succeeded Denonville as Governor for the next nine years (1689–1698). Frontenac had been arranging a new plan of attack to mollify the effects of the Iroquois in North America and realized the danger of the imprisonment of the Sachems. He located the 13 surviving leaders and returned with them to New France that October 1698.
During King William’s War (North American part of the War of the Grand Alliance), the Iroquois were allied with the English. In July 1701, they concluded the “Nanfan Treaty”, deeding the English a large tract north of the Ohio River. The Iroquois claimed to have conquered this territory 80 years earlier. France did not recognize the validity of this treaty, as it had the strongest presence within the area in question. Meanwhile, the Iroquois were negotiating peace with the French; together they signed the Great Peace of Montreal that same year.