Byzantium/Constantinople was conquered in 1451, but the empire continued to decline starting around the 18th or 19th centuries. It officially died in WWI. As for how long it was a major threat to Europe, the empire's prime was the 16th century, under Suleiman the Magnificent.
Explanation:
By the early 1700s, the fur trade was firmly established in the Great Lakes region. The French empire was based on the fur trade in this region and required Native American alliances to sustain it. Native people and the French traded, lived together, and often married each other and built families together.
Well, as a patriot our strengths are that we know this land, our families are at stake, and that we fight for what we believe in. We will win this war because we are fighting for what we think is right. Unlike the British redcoats who are fighting because their king has made them. If we lose this fight the lives of our families are at stake and the mercy to the redcoats as well as our posterity.
Pagers were invented in 1949 by Al Gross well the first telephone pager but it wasn't until 1956 when the motorola company creates the first portable paging device.