The first years in Montréal were difficult ones. A number of clashes between the colonists and the Iroquois claimed the lives of many victims on either side. In order to better protect the inhabitants of Montréal, a number of forts and fortlets were built on the island. These defensive posts were generally located in strategic locations. According to a geographic map belonging to the Sulpicians of Montréal, there were nearly twenty forts in Montréal in 1721, including Rolland, Rémy, Cuillerier and Verdun. These forts were generally made of wooded palisades, which were sufficient to thwart the Iroquois attacks.