Which of King Hrothgar's accomplishments dominates section 1? Why is this accomplishment important?

Like his ancestors, Hrothgar has kept the kingdom prosperous through winning battles and honoring his warriors. He decides to build a lavish hall named Heorot. Soon it is finished, and it becomes a great hall of feastingŠ until the demon Grendel hears the happiness in the hall and wishes to destroy it. Thus Grendel begins the bloody, 12-year rampage on Heorot that leaves Hrothgar and his people powerless to stop him.