President George Washington and the founders did not immediately in our Constitution cease the importation of slaves for the same reason people say the Confederates fought. These reasons are economics, free labor, etc. See Article 1 Section 9 of the US Constitution which prohibited cessation of importation of persons (slaves) before 1808. Note that even then they did not say it had to end in 1808. In fact the wording by the founders allowed such importation to continue indefinitely. Article 1 Section 2 also permits and encodes slavery principles in the initial Constitution. The founders set the stage for the necessity of various amendments and the Civil War.
Yet, to their credit the founders did seem to recognize and encode in our Constitution that slavery was incompatible with our nation’s goals. They seemingly did not want to fight the battle that the Civil War became. They seemingly did not want to do so because they believed it would prevent the formation of the United States of America. They were probably right.
So in essence the Civil War was the delayed war which they recognized would eventually probably come. They also recognized the amendment process provided hope for liberty for all or at least they left it up to later generations to make that decision for or against liberty for all. As you can see our history is complicated. Indeed, sin complicates matters.