How was the makeup of the military forces in World War I a direct result of imperialism?

Historians are concerned with the accuracy of their writings and readings but are also aware of the inability of authors to know every angle of every story biases, perspectives, beliefs, and a variety of other differences history being told by one person at a time no one being totally accurate, as hard as we try really need on this, and you^^

What is the name for the main idea behind the settling of western lands by americans in the early-1800s?

2. what was the dred scott decision about? what do we learn from this supreme court case?