During the war, Solomon was twice arrested by the British; in 1776 he was arrested as a spy and served as a German interpreter for the British military's Hessian mercenaries. In 1778 Solomon was sentenced to death, but escaped to Philadelphia, where he acted as a broker for the Office of Finance. Solomon worked extensively with Robert Morris, the Superintendent for Finance for the Thirteen Colonies, and is mentioned nearly seventy-five times in Morris' personal correspondence relating to the financing of the Revolution. Solomon also provided financial services to Continental Congressional delegates James Madison and James Wilson, and during the War became the broker to the French consul, the treasurer of the French Army that aided the Continental Army, and the fiscal agent of the French minister to the United States.
He sold bills of exchange for the French, and those funds went to pay the French military during their stay in Philadelphia. That is why some mistakenly believe he was the paymaster-general of the French forces in the early years of the United States.
Often working out of the "London Coffee House" in Philadelphia, he acted as a broker for the Office of Finance. Solomon sold about $600,000 in Bills of Exchange to his clients, netting about 2.5% per sale. During this period he had to turn to his client in the Office of Finance, Robert Morris, when one sale of over $50,000 nearly sent him to prison. Morris used his position and influence to sue the defrauder and saved Solomon from default and disaster.
After a solid career in Philadelphia, he saw opportunity in a different state. Former client Robert Morris tried to help him establish himself in New York. He died shortly after he had decided to move back to city and become an auctioneer there.
His obituary in the Independent Gazetteer read, "Thursday, last, expired, after a lingering illness, Mr. Haym Solomon, an eminent broker of this city, was a native of Poland, and of the Hebrew nation. He was remarkable for his skill and integrity in his profession, and for his generous and humane deportment. His remains were yesterday deposited in the burial ground of the synagogue of this city."
The gravesite of Haym Solomon is at Mikveh Israel Cemetery, located on the 800-block of Spruce Street, in Philadelphia. It is unmarked, but he has two plaque memorials there. The east wall has a marble tablet that was installed by his great-grandson, William Solomon, and a granite memorial is set inside the gate of the cemetery. In 1980, the Haym Salomon Lodge #663 of the fraternal organization B'rith Sholom sponsored a memorial in Mikvah Israel Cemetery on the north side of Spruce st. between 8th and 9th Sts. in Philadelphia. A large, engraved memorial marker of Barre Granite just inside the cemetery gates was placed, inscribed, "An American Patriot".
When Solomon died, it was discovered he had been speculating in various currencies and debt instruments. His family sold them at market rates, which had greatly depreciated because of the weakened state of the American economy in the 1780s. Subsequent generations misunderstood his truly patriotic actions and appealed to Congress for more money, but were turned down twice. A myth grew up that he had lent the young United States government about $600,000, and at his death about $400,000 of this amount had not been repaid. This sum was added to what he really had lent to statesmen and others while performing public duties and trusts. Jacob Rader Marcus wrote in Early American Jewry that the sum owed to Solomon was $800,000. That amount in 1785 is equivalent in purchasing power to about $39,264,947,368.42 (using relative share of GDP which indicates purchasing power) in 2005 US dollars.
Solomon spoke eight languages. Supposedly, when he was in France, he passed himself off as a French diplomat. Unfortunately, it does not conform to the known facts. It is true his co-religionist, David Franks, did help Adams negotiate loans from Holland. However, there is nothing in the record to show that Solomon himself went to Europe for this purpose.
Solomon is sometimes alleged to have written the first draft of the United States Constitution but the Philadelphia Convention occurred after his death. Others have claimed that he designed The Great Seal of the United States and that he included the Star of David, a Jewish symbol, above the eagle's head. There is no documentary evidence to support this claim.
It is often said that Solomon lent hundreds of thousands of dollars to the Revolutionary government, which never repaid him. In fact, the money merely passed through his bank accounts.
The Congressional Record of March 25, 1975 reads, "When Morris was appointed Superintendent of Finance, he turned to Solomon for help in raising the money needed to carry on the war and later to save the emerging nation from financial collapse. Solomon advanced direct loans to the government and also gave generously of his own resources to pay the salaries of government officials and army officers. With frequent entries of 'I sent for Haym Solomon,' Morris' diary for the years 1781–84 records some 75 transactions between the two men."
In 1939, Warner Brothers released Sons of Liberty, a short film starring Claude Rains as Solomon. Hollywood film producer John C. W. Shoop, under direction of MorningStar Pictures, is currently in production of a story of the life and times of Haym Salomon called On The Money.