What caused spain's and portugal's demands for african slaves to grow?

The Spanish and Portuguese were in need of colonial labor force so they had to increase the source for African slaves.

Explanation:

Demand for African slaves was high and the slave trade was controlled by the Portuguese, who set up trading posts on the west coast of Africa. Spanish colonists purchased them directly from Portuguese traders, who in turn purchased them from African traders on the Atlantic coast.

As a result, it was Spain, rather than Portugal, that first made extensive use of enslaved Africans as a colonial labor force.

when world war i broke out across europe in 1914, president woodrow wilson proclaimed the united states would remain neutral, and many americans supported this policy of nonintervention. however, public opinion about neutrality started to change after the sinking of the british ocean liner lusitania by a german u-boat in 1915; almost 2,000 people perished, including 128 americans. along with news of the zimmerman telegram threatening an alliance between germany and mexico, wilson asked congress for a declaration of war against germany. the u.s. officially entered the conflict on april 6, 1917.