Ion Perdicaris' father, Gregory Perdicaris, was a Greek who had emigrated to the United States from Athens, marrying into a wealthy family in South Carolina and becoming a US citizen. He later returned to Greece as US consul. In 1846 the family moved to Trenton, New Jersey, where Gregory Perdicaris became wealthy as one of the organizers of the Trenton Gas Company. His son Ion lived the life of a dilettante until the American Civil War. By 1862, the family's property in South Carolina was in danger of confiscation by the government of the Confederate States of America. Ion Perdicaris travelled to Greece, intending to renounce his United States citizenship and acquire Greek nationality to forestall any confiscation.
Ion Perdicaris later moved to Tangier, where he built a house known as the Place of Nightingales and filled it with exotic animals. In 1871, Perdicaris met Ellen Varley, wife of the eminent telegraph engineer C.F. Varley in Malvern, England. Varley was away on a cable-laying expedition and Ellen abandoned him for Perdicaris. The Varleys divorced in 1873 and Ellen settled in Tangier with Perdicaris and her two sons and two daughters. Fascinated by Moroccan culture, Perdicaris wrote several books (few of them published to a wide audience) on Morocco, and became the unofficial head of Tangier's foreign community. He maintained business interests in England and the United States and frequently visited New York.
On 18 May 1904, Perdicaris, and Ellen's son Cromwell, were kidnapped from their home by Mulai Ahmed er Raisuli's bandits. Several of Perdicaris's servants were injured by Raisuli's men, and Ellen was left behind alone. Shortly after leaving Tangier, Perdicaris broke his leg in a horse fall. Raisuli demanded of Sultan Abdelaziz of Morocco, $70,000 ransom, safe conduct, and control of two of Morocco's wealthiest districts.
Despite the circumstances, Perdicaris came to admire and befriend Raisuli, who pledged to protect his prisoner from any harm. Perdicaris later said: "I go so far as to say that I do not regret having been his prisoner for some time... He is not a bandit, not a murderer, but a patriot forced into acts of brigandage to save his native soil and his people from the yoke of tyranny." 
US president Theodore Roosevelt was angered by the kidnapping, and felt obliged to react. His Secretary of State, John Hay, described the demands as "preposterous". At the urging of Hay and the Consul-General of Tangier, Samuel R. Gummere, Roosevelt dispatched seven warships under the command of Admiral French Ensor Chadwick, and several Marine companies, commanded by Major John Twiggs Myers, though with little idea of what US forces could achieve on such hostile foreign soil. They were not to be used without express orders from Washington; the only plan for using them was to seize the custom-houses of Morocco, which supplied much of its revenue, if the Moroccan government did not fulfill the demands of the United States, which were to make the concessions necessary to persuade Raisuli to release Perdicaris, and to attack Raisuli if Perdicaris were killed anyway. The only Marines actually to land on shore were a small detachment of a dozen men, carrying only side-arms, who arrived to protect the Consulate and Mrs. Perdicaris.
Roosevelt's resolve weakened when he was advised on 1 June that Perdicaris was not a US citizen, that in fact he had forfeited his American passport for a Greek one forty years earlier; but Roosevelt reasoned that, since Raisuli thought Perdicaris was an American citizen, it made little difference. Roosevelt tried to get Britain and France to join the US in a combined military action to rescue Perdicaris, but the two countries refused and France actually reinforced its garrison in anticipation of an American assault. Instead, the two powers were covertly recruited to put pressure on the Sultan to accept Raisuli's demands, which he agreed to do on 21 June. Hay saw the need to maintain face so he issued a statement to the Republican National Convention:
This government wants Perdicaris alive or Raisuli dead.
According to all witnesses, the Convention, which had been lukewarm towards Roosevelt up until then, went wild at this remark. One Kansas delegate exclaimed, "Roosevelt and Hay know what they're doing. Our people like courage. We'll stand for anything those men do."  This famous catchphrase quickly caught on, and helped Roosevelt secure his election.
Perdicaris and Varley were met personally by Gummere and Chadwick, who had spent much of the time of their capture with Perdicaris's wife. When Ellen Varley asked for the admiral to provide a doctor for her husband, every medical officer in the American fleet volunteered.
Perdicaris and his family moved to England shortly after the incident, eventually settling in Tunbridge Wells. He occasionally returned to Trenton where he maintained business interests. Perdicaris Place, off West State Street, is named for him and his father. Ion Perdicaris died in London in 1925.
"Hostages to Momus", a short fiction story by the American author O. Henry was inspired by the kidnapping of Ion Perdicaris, who in the story is referred to as "Burdick Harris" ("Bur-dick-Harris" is a play on "Per-dic-aris", as the names rhyme, if pronounced as the author intended), a Greek citizen. The humorous story was written shortly after the incident.
In 1924, British author and adventurer Rosita Forbes published The Sultan of the Mountains: The Life Story of the Raisuli, a full-length biography of Raisuli; the book is currently out of print in English, but a Spanish translation has appeared recently. Other books have discussed the incident, including David S. Woolman's Rebels in the Rif, Michael B. Oren's Power, Faith and Fantasy: America in the Middle East, 1776 to the Present and Bill Fawcett's Oval Office Oddities, and a lengthy, in-depth chapter on the kidnapping and President Roosevelt's reaction is included in Edmund Morris's second Roosevelt biography, Theodore Rex.
The story of Ion Perdicaris's kidnapping was loosely adapted to film in the 1975 motion picture The Wind and the Lion, with Sean Connery in the role of Raisuli and Brian Keith as Roosevelt. However, to add some spurious glamour to the tale, the 64-year-old bearded hostage was replaced with attractive young "Eden Pedecaris", played by Candice Bergen. While the movie incorrectly showed US Marines invading Morocco, not to mention their bizarre battle with non-existent soldiers of the German Empire, it succeeded in presenting the personality of Raisuli and his interaction with his prisoners.
- "1904: 'Perdicaris alive or Raisuli dead!'", Jon Blackwell, The Trentonian.
- Barbara Tuchman, "Perdicaris Alive or Raisuli Dead" in Practicing History (1982); originally published in American Heritage X, 5 in 1959.
- Edmund Morris, Theodore Rex, p. 335.
- Barbara W. Tuchman, "Perdicaris Alive or Raisuli Dead!". American Heritage, August 1959; later republished in Tuchman's essay compilation Practicing History: Selected Essays (1984), pp. 104-117
- "Hostage to Momus" online
- Amazon.com page on Forbes' book
- 'El Raisuni, sultán de las montañas', Editorial Almuzara (2010), ISBN 978-84-92924-07-3