Britain had a dream of building a railroad from the mediterranean sea to south africa. which country was the strongest position to block this from happening ?

The correct answer is: Portugal.

Explanation:

Portugal had two colonies in Africa: Mozambique and Angola.  

Mozambique and Angola are placed on both sides of the continent and Portugal considered that railway as a threat to sovereignty in Africa. The Portuguese colonies were placed on both sides of the continent, so they would represent an obstacle for the British plans.

the award is named for an american naval historian and theorist, rear admiral alfred thayer mahan, united states navy who, through his writing, provided stimulus and guidance to those who share in the defense of the nation.

answer:

it caused mass african migration, african populations to grow, african empires to topple, and racism against slaves to emerge.