Born in Ireland, Hickey came to America as a soldier in the British Army and fought as a combat field servant to Major General William Johnson in the Seven Years' War.

He later joined the Patriot cause when the American Revolution broke out, and became part of the Life Guard, which protected General George Washington, his staff, and the Continental Army's payroll.

Thomas Hickey was a private in the Commander-in-Chief's Guard, a unit formed on March 12, 1776, to protect George Washington, his official papers, and the Continental Army's cash.

During the trial, David Mathews, the Mayor of New York City and a Loyalist, was accused of funding the operation to bribe soldiers to join the British.

A most infernal plot has lately been discovered here, which, had it been put into execution, would have made America tremble, and been as fatal a stroke to us, this Country, as Gun Powder Treason would to England, had it succeeded.

[10] A garbled account of an assassination attempt appeared over two years later in a provincial English newspaper, The Ipswich Journal, on October 31, 1778: Advise is received from America that two persons, a man and a woman who lived as servants with General Washing ton [sic], have been executed in the presence of the army for conspiring to poison their master.

[11]In a March 5, 1785, sworn petition to the U.S. Congress, Samuel Fraunces claimed that it was he who discovered the assassination plot, that he was falsely accused of being part of it and was jailed until his name was cleared.

Two years later, his daughter, Mary Anna Custis Lee, published his memoirs, to which were added extended notes by the antiquarian Benson J. Lossing.

[Samuel] Fraunces's daughter was Washington's housekeeper, and she saved his life on one occasion, by exposing the intentions of Hickey, one of the Life-Guard (already mentioned), who was about to murder the general, by putting poison in a dish of peas prepared for his table.

Davis), by the late Peter Embury, of New York, who resided in the city at the time, was well acquainted with the general's housekeeper, and was present at the execution of Hickey.

It was nationally read in the patriotic build-up to the 1876 Centennial celebration: A daughter of "Black Sam", Phoebe Fraunces, was Washington's housekeeper when he had his headquarters in New York in the spring of 1776, and was the means of defeating a conspiracy against his life.

Its immediate agent was to be Thomas Hickey, a deserter from the British army, who had become a member of Washington's bodyguard, and had made himself a general favorite at headquarters.

[21]In 1919, Henry Russell Drowne (great-grandson of Dr. Solomon Drowne, the 1776 chronicler above) repeated the Phoebe Fraunces legend in his history of Fraunces Tavern: His [Samuel Fraunces's] daughter Phoebe was Washington's housekeeper in the Mortier House on Richmond Hill, occupied by the Commander-in-Chief as Headquarters, in June, 1776, and it was she who revealed the plot to assassinate Generals Washington and Putnam, which led to the apprehension of her lover, an Irishman named Thomas Hickey, a British deserter, then a member of Washington's bodyguard, in consequence of which he was promptly executed on June 28, 1776.

Self-published author Charles L. Blockson states that "Phoebe" was the nickname of Fraunces' eldest daughter Elizabeth, but he provides no evidence to support this claim.