What problems with the original Constitution, or changes in society, led to the 13th through 15th amendments.
The change in society that led to the 13th through 15th Amendments was the Civil War. Because of the Civil War, the people of the North felt that it was necessary to pass these amendments, which are collectively known as the "Civil War Amendments."
At the time the Constitution was written, slavery formed the basis of the Southern economy and had to be accomodated in order to get the South to ratify the document. The differences between the slave South and the free North eventually led to the Civil War. After that war, the North did not want the South to go back to having the "peculiar institution" that had been the cause of the sectional animosity. Because of this, the North felt it was important to amend the Constitution to end slavery and to give freed blacks rights that were at least officially equal to those of whites.
The civil war led to the 13th through 15th amendments. The civil war was a fight between the north and south over slavery. The north who thought slavery didn't make any sense won the war, and in order to make sure the win was acknowledged they passed the amendments to insure the south would not continue slavery. Also the amendments made sure free blacks got their freedom at a certain level and that they had rights.