Why was the invention of the magnetic compass important?

It made navigation much, MUCH easier.

Explanation:

Normally, people relied on staying  close  to the shore to avoid getting lost. Only the bold would go out farther.  But with the invention of the  magnetic compass- you could go much further as you had a sense  of direction.  You could still get lost,  but you could likely find your way back.

lincoln presided over the union victory in the american civil war, which dominated his presidency. a former whig, lincoln ran on a political platform opposed to the expansion of slavery in the territories. his election served as the immediate impetus for the outbreak of the american civil war.

d) all choices are correct