Biographical material on O'Fallon (or just Fallon) is rather sketchy but, according to Family Treemaker.com, James O'Fallon was born to William O'Fallon and Anne Eagan near Athlone, County Roscommon, Ireland on March 11, 1744 or 1745. Later, after he had moved to Kentucky, Dr. O'Fallon left to his descendants a record of the genealogy of the O'Fallon family which confirms his parentage and states that they were of Ballyna House. This would indicate that his parents were people of means and thus could have afforded to send him to medical school there in Ireland. Under the heading of "Col. John O'Fallon" (James O'Fallon's younger son, born in 1791) in the Northern Illinois University Libraries Digitization Projects, John O'Fallon's father, the James O'Fallon in question, was "...an Irish gentleman of education." (page 79).
(Note: John Carl Parish, "The Intrigues of Doctor James O'Fallon", Mississippi Valley Historical Review, Vol. 17, No. 2 (Sept. 1930) pp. 230-263 states on page 230 of this article that James O'Fallon was born on March 11, 1749. As a matter of fact, Parish notes that the only real information (as of September 1930) we have on the early life of James O'Fallon comes form some information given to Lyman Draper well after O'Fallon had settled in Kentucky. Noted for its scathing indictment of James O'Fallon is this rather lengthy article by Parish. It literally begins with "Side by side with machinations of James Wilkinson in the unquiet region of the Trans-Allegheny were the intrigues of a number of lesser characters....Notable among these contemporaries was Doctor James O'Fallon. (page 230.))
He is recorded as emigrating to the American colonies in 1774 and initially settled in Wilmington, NC. The same source cited above for James O'Fallon also states that he emigrated to America in 1774 and settled in Wilmington, NC. He must have received his medical training while in Ireland because when the American Revolution broke out, he became Surgeon-in-Chief for the Continental Army. He was the oath of allegiance at Valley Forge under the command of General George Washington. Again, the NIU Libraries Digitization Project fills out the description of his early Revolutionary War activities. It states that initially, James O'Fallon was very outspoken in his support of the patriot cause and was imprisoned by the Royal Governor of North Carolina for his rebel publications. He was freed from this incarceration by General Ashe and 800 militiamen. He then proved instrumental in causing the governor to flee the colony, never again returning to it. Later, O'Fallon raised a troop of one hundred Irishmen in Georgia and was appointed as their captain as a result of mustering them. He remained in this capacity from 1775 until the Battle of Brandywine in 1777. Afterwards, he offered his services as a trained surgeon and was appointed surgeon of the General Hospital of the United States until the conclusion of the war in 1783.
Again, there is scant evidence as to how he came to be associated with the frigate South Carolina. In Samuel Cole Williams's History of the Lost State of Franklin, (Press of the Pioneers, New York, 1933) James O'Fallon is cited as being "...of Charleston and later of Kentucky." If this is true, then he must have relocated to Charleston at some point in time but, when exactly is the question. It may have been during the war, in which case Gillon and he could have easily met or come to the attentions of each other through reputation. Thus, O'Fallon could have journeyed across the Atlantic Ocean in company with Commodore Gillon or he could have been sent over there as a trusted aide of Gillon. Moss in his work, Roster of South Carolina Patriots in the American Revolution, on page 302, for the entry "James Fallon" simply states that "he served aboard the frigate South Carolina". O'Fallon receives scant coverage in Dr. Lewis's book, Neptune's Militia, and in the section on "Roster of the Crew and Marines on Board the South Carolina" on page 146 beside the name "James Fallon (O'Fallon) there is the rather cryptic entry "Surgeon?"
Both Gillon and Fallon/O'Fallon gained enemies during their lifetimes. Yet, the name of either, associated with the other, casts further disparage upon that one. In his work, Neptune's Militia, page 130, Dr. Lewis states of Gillon that "...hostile observers linked his name with James O'Fallon (or just Fallon), an Irishman who may have served on Gillon's frigate. O'Fallon was apparently an ex-priest who speculated in shady land titles along the American's borders with Spanish Florida and Louisiana. Spanish authorities mentioned his name frequently." As an example of his "shady land titles" dealings, Williams in his work, History of the Lost State of Franklin, page 243, says that "...he proposed a colony of Catholics, mostly Irish, on a grant of land from Spain sufficient to give 857 acres each to 5,000 heads of families to be settled within a period of seven years. The location of this proposed concession was along the debatable northern margins of East Florida." As one can easily see from this blog, the spelling of the man's last name is even in question - whether Fallon or O'Fallon. It may well be the case that he did not want a great deal of information circulating concerning him. He may have deliberately kept in the shadows until he had made name for himself in society, even in the frontier society of early Kentucky.
After the conclusion of the war, James O'Fallon removed to Kentucky and later married Frances Eleanor Clark, the youngest sister of George Rogers Clark of Kentucky Revolutionary War fame. They had two sons, John O'Fallon born on November 17, 1791 and Benjamin O'Fallon born on September 20, 1793. James O'Fallon died in Louisville, KY in 1794. Here at the end of it all, Dr. James O'Fallon had legitimized himself in the eyes of society.