Complex sentence: The British paroled the American forces, essentially allowing them to go free after swearing to not take up arms in the war again, and made the island inhabitants to swear an oath of allegiance as subjects of the United Kingdom.
Split into simpler sentences: The British paroled the American forces, essentially allowing them to go free after swearing to not take up arms in the war again. They made the island inhabitants swear an oath of allegiance as subjects of the United Kingdom.