While Grotius's work was well known & read among the educated colonists, his works tended to include too much of the german civil code of allegiance which was heavily weighted in feudal doctrine of perpetualness. The german’s reasoning was that God was the Supreme and thus the church was God's earthly representative, no man could remove himself from his duty to the Church. This was the case also in England, the King & the Church were one. It is the heart of feudal law that didn't seed a permanent hold in England until the late 1500’s. The truth is, the church dictated much of the laws that got passed. It also dictated the execution/English holocaust of 1000’s of catholic parishioners based purely on their religion in Ireland that directly lead to the England conquering Ireland. Grotius, Pufendorf, Sidney & Locke's works weighted heavily on religion and all spoke of some allegiance to the Almighty that could not be cast off. However, by the time of Sidney & Locke, the right of expatriation finally got it's proper place so that when Vattel’s works came along, natural law of nations was the prominent dictate & religion became the lesser.
The big misnomer today is that Grotius, Pufendorf, Sidney & Locke were works of laws of nations when in fact they were largely works on natural law with a splash of law of nations & right of movement. Locke's works disputed Grotius and lead the path to the right of movement and the dismantling of the feudal doctrine of perpetual allegiance in England that is now the law today. Children born to aliens in England today, do not get British citizenship. But unfortunately for them, it may have come too late. For us, we still have time, but the clock is ticking on this subject.
The Franklin letter to Dumas thanking him for the copies of Vattel’s Law of Nations stating it was being put to good use by the “Congress now sitting” was signed by Franklin, John Dickinson and John Jay.
B. Franklin.
Mons. Dumas.
Philadelphia Dec. 12. 1775.
We the underwritten, appointed by the american congress a committee of foreign correspondence having perused the above Letter, Written at our Request, do approve and confirm the same.
(Signed) John Dickinson
John Jay
http://www.franklinpapers.org/franklin/framedVolumes.jsp