Where in all of bilbos magnificent and often difficult adventures is his real battle

Bilbo's natural timidity and preference for the status-quo of Hobbit life is always a challenge to him. For much of the novel Bilbo is a reluctant anti-hero who must summon all he has in order to rise to the occasion. I think this is his main challenge. Also using his inner strength to combat the lure of the ring take all Bilbo has.