East of Germany, fighting broke out in a vast area that came to be known as the Eastern Front. Russian troops had mobilized more quickly than the Germans thought possible. Two Russian armies thrust deeply into a region of forests and marshy lakes in eastern Germany. The Germans drove the Russians back. In two battles, the Russians suffered nearly two hundred fifty-thousand casualties.

Using context clues in the paragraph, determine the meaning of mobilized

Question 2 options:

fought

dismissed

organized