Why did many of the delegates at the Constitutional Convention oppose the ratification of the Constitution?
One reason was the lack of the Bill of Rights protecting the rights of individuals from the power of the a strong federal government.
The Revolutionary War was fought to a large extent as a reaction to the tyranny of England not respecting the rights of individuals. The so called right of an Englishman were trampled on by the central government of England in the colonies.
Colonial legislatures were dissolved by the crown and replaced with governors that ruled by executive orders. Soldier were lodged in private homes with payment or permission. People were brought before Judges without a jury of their peers Taxes were approved with input from the people being taxed.
without some guarantees that the new federal government would not result in tyranny over individual rights many delegates could not support the Constitution.