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Both countries were forced to industrialize by aggressive neighbors
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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.
James Madison<span>, also present, wrote the document that formed the model for the Constitution. Other </span>U.S. Founding Fathers<span> were not there, but made significant contributions in other ways. </span>Thomas Jefferson<span>, who wrote the Declaration of Independence, was serving as ambassador to France at the time of the Convention</span>