During the Revolutionary War, the Articles of Confederation were the US Constitution at the time, but the Articles created a weak central government and strong state governments. This satisfied the States' needs but it created a series of other problems because the Central Government did not have several powers that could maintain it working, it depended on the State's will to give it money, for example, this caused debt and created an uncoordinated country.
After the Revolutionary War, the US needed to become a strong united country and the Articles did not provide that, so they wrote the Constitution, which created a strong central government at the same time that gave the States power.