He was the French ambassador, Charles Genet. The French government helpfully sent him to the U.S. to enlist support for war with England, which he began to do as soon as he set foot on American soil. Incredibly popular with the American public, “Citizen Genet” was given a hero's welcome when he arrived. He was in no hurry to pay President Washington a visit, instead spending time with his adoring American fans. He promptly began seizing British ships and transforming them into a fleet of privateers, partly manned by Americans, and trying to instigate war with Spain over Florida. By the time he finally got to the Capital, Washington was away. He was received by the Secretary of State instead, Thomas Jefferson, who informed him that the U.S. would not participate in any of his plots. Undeterred by repeated cease-and-desist orders from the US Government, he continued mischief-making until President Washington, thoroughly fed up, demanded that France recall him.
Ironically, though, by this time, the government that sent him had been toppled. If forced to return to France, he would most likely lose his head in the French Revolution that he was so eagerly collecting support for. Washington relented and allowed him asylum.
Perhaps Genet had finally learned his lesson. He soon married an American girl and settled down, never causing any more trouble.