Complex sentence: It is not clear whether this reference is to Uncle Sam as a metaphor for the United States, however the lyrics as a whole clearly deride the military efforts of the young nation, besieging the British at Boston.
Split into simpler sentences: It is not clear whether this reference is to Uncle Sam as a metaphor for the United States. The lyrics as a whole clearly deride the military efforts of the young nation, besieging the British at Boston.