Why was the Iroquois League formed?

Basically to defend themselves against enemies.

Five American Indian tribes, sharing the Iroquois language, form a defensive league in the late 16th century against their enemies, the Huron. ... According to Indian tradition the league is founded by Hiawatha, a leader of the Mohawks, on the inspiration of a holy man, Deganawidah.

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".

im not sure on this one