I believe the tv series came first then the book was written as a companion. The Pacific is really good althought not as popular as BOB and definitely worth watching. One of the nicest things about The Pacific is that both childhood friends Eugene Sledge and Sidney Phillips served in the war and survived. Phillips is younger by one year but entered the served two years before his friend because Sledge's dad refused promission for his son to join up. Here is an interview Sledge gave before his death in 2001 and a photo of both Sledge and Phillips.