According to document 2, why did east africans have to risk their livelihoods to fight the germans?

The German force in East Africa was to obliged by the Allied governments to retain military forces and provisions in Africa, rather than conveying them to fight in Europe. They threatened the important British Uganda Railway, in order to conquer East Africa, where they will be able to combat a cautious action. In 1912, the German government was able to formulate a security tactic for East Africa in which the military would pull out from the shore into the vicinity and fight a guerrilla crusade.