American shipping interests in the Mediterranean faced a constant threat from Muslim pirates who viciously attacked commercial vessels as much for their crews as for their cargoes.
It's true that Thomas Jefferson owned a Koran, but his reason for studying it went beyond a desire to understand another religion. He was preparing to lead the nation in war with Muslim terrorists! At the time of his presidency, one sixth of American wheat and flour exports traversed the Mediterranean Sea, as well as one fourth of its pickled and dried fish exports.
These products represented a sizable portion of the young American country's trade. The commodities, as well as the crews that transported them, were being attacked by Muslims.
From the late 1500s, shipping in the Mediterranean faced a constant threat from Muslim pirates who viciously attacked commercial vessels as much for their crews as for their cargoes. These were the infamous Barbary pirates, named after the states of the Barbary Coast, modern Morocco, Algeria, Tunisia and Libya. The pirates were state-sponsored, backed by the Ottoman Empire.
They enslaved crews that they captured, using them to man the oars on the pirate vessels. Any women taken were shipped to markets to be sold as concubines. Captured young boys were mutilated to create eunuchs, who would bring higher prices in the slave markets.
Until the American Revolution, the British Royal Navy protected ships from the colonies that sailed the Mediterranean. During the war, an alliance with France brought the American vessels under its protection, but after winning independence, the United States had to fend for itself. European nations at the time attempted to lessen the threat from the pirates by paying them "tribute money," essentially a protection racket. In exchange for the bribes, the pirates would not attack.
However, the agreements were flimsy and often broken. When the pirates took captives, they would demand ransom money from the crew's home nation. Initially, the fledgling American Congress followed the European model, paying tributes and ransoms, until the amounts reached a staggering 20 percent of America's national revenue by 1800!
Jefferson's first encounters with the Barbary pirates stemmed from his service as ambassador to France in 1786. From the beginning, he opposed paying anything to the pirates. He asked Tripoli's ambassador to Britain why the Barbary States were so hostile to America.
The frank reply: "It was founded on the Laws of their Prophet, that it was written in the Koran, that all nations who [sic] should not have acknowledged their authority were sinners, that it was their right and duty to make war upon them wherever they could be found, and to make slaves of all they could take as Prisoners, and that every Musselman who should be slain in Battle was sure to go to Paradise" (Joshua E. London, "America's Earliest Terrorists," National Review Online, Dec. 16, 2006).
We should note that this was over 160 years before the formation of the state of Israel, so this Muslim antagonism against America cannot be written off as caused by American support for Israel.
When Jefferson assumed the presidency in 1801, he ordered the U.S. Navy to the Mediterranean, refusing to pay either tribute or ransom any longer. The U.S. Marines pounded the Barbary positions from the sea, and a small expedition actually went overland to help some rival Muslim forces take Tripoli, giving inspiration to the line in the Marine hymn, "from the halls of Montezuma, to the shores of Tripoli..." WNP