The Confederation was replaced by the United States Constitution due to its unicameral nature and a desire for a more 'national' government. The Great Compromise resolved issues regarding representation in Congress, with the House of Representatives based on population and each state having two members in the Senate. Slavery was also a contentious issue, with debates surrounding counting slaves as three-fifths of a person and the trade being halted until 1800. Despite these challenges, the Constitution established the legislative, executive, and judicial branches of government, emphasizing national unity and allowing for amendments through a two-thirds approval from Congress and three-fourths vote from states.