The Great Compromise was an agreement that large and small states reached during the Constitutional Convention of 1787. . It basically defined the legislative structure and representation each state could have. Each state would have 2 Representatives.
There were many conflicts over representation in the south. The constitutional convention agreed to count the three-fifths compromise. This counted slaves as population for purposes of representation and taxation. (Even though slaves couldn't vote, the slaveholders vote would now hold more weight) there were more "citizens" in the northern states, so the south felt underrepresented.
A special-purpose government.