This tough old adverb, preposition, conjunction, and adjective with a poetical and old-fashioned sound is still an active word in the OED.  There are obsolete meanings for “ere” which overlap with the uses we see here.  It’s used in solemn dwarvish poetry in the Shire, and outside of the Shire during parleys between leaders after chapter 10.  And the narrator uses it.  Our narrator only lets his personality show once in a while – usually speaking directly to the reader/listener.  He uses it in battle scenes – it sounds to me that the narrator has become excited into a higher-register state.  We’re going to keep our eye on these passages.  I’m labeling this one as both poetical and high.

• 01.073 We must away ere break of day
• 01.077 We must away, ere break of day,
• 01.082 We must away, ere break of day,
• 01.144 We must away, ere break of day,
• 15.053 Begone now ere our arrows fly!
• 15.054 Gather your wisdom ere we return!’
• 15.055 Ere many hours were past, (narrator)
• 17.037 ere I begin this war for gold.
• 17.048 Ere long the vanguard swirled (narrator)
• 19.007 Ere long now,’

“ere, adv.1, prep., conj., and adj.” OED Online. Oxford University Press, March 2015. Web. 11 May 2015.