Regulate commerce in both the North and the South, but could not yet regulate the slave trade.
Explanation:
The constitutional convention was made to write a new constitution for the USA, in that convention were solved many problems, among these problems, the guidelines between commerce and the slave trade were resolved. In this regard it was decided that the Congress could not prevent the slave trade, but a tax would be levied on each imported slave.
The use of submarines made attacking or torpedoing ships easily, that made attacking more effective and reduced the chance of home soldiers getting killed.
The Constitution lists only three qualifications for the Presidency — the President must be 35 years of age, be a natural born citizen, and must have lived in the United States for at least 14 years.