Even if we're not familiar with the history we think we know the ending. The success of 1776 owes less to the score than the clever book which manages to generate suspense and leave the ending in doubt.
Being cast in the show is a fun but strange experience. The soloists tend to sing their song then vanish. The congressmen are on stage for most of the show but many stop singing after the opening number.
Edit: Fixed a typo and increased the font size.