Did you ever wonder why the Marine Corps Hymn starts with the words:
From the Halls of Montezuma
To the shores of Tripoli
The “shores of Tripoli” refers to our military’s first battles against Muslim terrorists.
The Barbary Powers conflict began during the American Revolution when Muslim terrorists from four different Islamic nations (Tunis, Morocco, Algiers, and Tripoli) began making indiscriminate attacks against the property and interests of what they claimed to be “Christian” nations (America, England, France, Spain, Portugal, Denmark, Sweden, etc.).
The Barbary Powers (called Barbary “pirates” by most Americans) attacked American civilian and commercial merchant ships (but not military ships) wherever they found them. Prior to the Revolution, American shipping had been protected by the British navy, and during the Revolution by the French navy. After the Revolution, however, America lacked a navy of her own and was therefore left without protection for her shipping. The vulnerable American merchant ships, built for carrying cargoes rather than fighting, were therefore easy prey for the warships of the Barbary Powers, which seized the cargo of the ships as loot and took their seamen (of whom all were considered Christians by the attacking Muslims) and enslaved them. 
In 1784, Congress authorized American diplomats John Adams, Benjamin Franklin, and Thomas Jefferson to negotiate with the Muslim terrorists.  Negotiations proceeded, and in 1786, John Adams and Thomas Jefferson candidly asked the Ambassador from Tripoli the motivation behind their unprovoked attacks against Americans. What was the response?
The Ambassador answered us that it was founded on the laws of their Prophet [Mohammed] – that it was written in their Koran that all nations who 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 [Muslim] who should be slain in battle was sure to go to Paradise.