In the 1760s he was involved in a project with fellow trader John Rae encouraging Irish immigration to the region. On the Georgia side of the Savannah River, these immigrants were encouraged to move onto a 50,000-acre (200 km2) tract of land called Queensbourogh.
During the American Revolution George Galphin sided with the Continental Congress, serving as one of its Indian Commissioners for the South. On May 1, 1776, the Creek Nation met as a whole with Galphin in a meeting he convinced the Creek Nation to remain neutral in the burgeoning conflict between the British and the revolutionaries. This successfully fustrated the efforts of the British to enlist sufficient Native American support throughout the South to overpower the comparatively small colonist population. Henry Laurens credited Galphin for helping to secure both Georgia and South Carolina for the Revolution.
At the time of his death in 1780, Galphin owned 40,000 thousands acres of land in South Carolina and Georgia along with 128 slaves, some of whom were his own children. His estate became involved in protracted litigation. His estate was at dispute in
REF: Colonial Period Archeology at Silver Bluff
http://www.georgiaencyclopedia.org/nge/Article.jsp?id=h-2873
http://en.wikipedia.org/wiki/George_Galphin