Complex sentence: Franklin earned the title of "The First American" for his early and indefatigable campaigning for colonial unity; as an author and spokesman in London for several colonies, then as the first United States Ambassador to France, he exemplified the emerging American nation.
Split into simpler sentences: Franklin earned the title of "The First American" for his early and indefatigable campaigning for colonial unity, first as an author and spokesman in London for several colonies. As the first United States Ambassador to France, he exemplified the emerging American nation.