In 1785, Barbary pirates captured the American merchant ship The Maria Boston, on its way to Cadiz carrying furs, lumber, and dried codfish.

During the 11 years of his slavery in Algiers, Cathcart managed by means of good fortune, cleverness, and bribery to improve his circumstances, eventually becoming chief clerk to the Dey.

[1] In that position, he acted as a mediator between the Dey and Joseph Donaldson Jr., an agent for Colonel David Humphreys, the U.S. Minister to Portugal, which resulted in the Treaty of Algiers of 1796 and allowed his freedom.

Although his assigned duties were relatively light, his masters provided scant food and administered several beatings, called bastinado; in one instance, Cathcart lost several of his toenails.

[4] Cathcart served in the diplomatic corps for the United States during the administrations of John Adams, Thomas Jefferson, and James Madison.