Final answer:
The greatest failure of the Constitution was the initial absence of a bill of rights and the struggle over the balance of power between federal and state governments, along with the omission of protections regarding slavery.
Step-by-step explanation:
The greatest failure of the Constitution, as perceived by many at the time of its ratification, was its lack of a bill of rights to explicitly protect individual liberties. Additionally, the struggle between the power of federal and state governments caused significant controversy. Critics like Patrick Henry feared the federal government's new powers, such as maintaining armed forces and imposing taxes, while supporters believed these measures were essential for the nation's survival. The absence of protections for slavery was another profound oversight, which would eventually lead to the Civil War and the need for the Reconstruction Amendments.