Explain the idea known as "nationalism" and how it played a role in the weakining of the austrian and russian empires

A heightened sense of patriotism, particularly during wartime.
this was highly present during the first world war with the American people. many would fight as a soldier. and those unable to do so would give money to the war effort and many even went to work in industries concerning the war. this made america a formidable force that helped weaken the mighty Russian/Austrian empires.