is this real and how did they survive 15 yrs straight .and how did his army get deafeted.

That's right. It only survived for 15 years since it was established.
As the Qin Ershi was too fatuous to well rule his country, there were much unsatisfaction among the people. And the area governors during that time rose up, the Shang army spent mush energy to defeat that. Therefore, when Zhou Wuwang wages a battle, the army had no power or energy to flight any more. Then they were defeated.