Barbary Pirates were pirates and conservatives who used to pillage and plunder in the Mediterranean for centuries with the approval of their Islammic governments. The Koran allows Muslims to enslave non-Muslims, see Slavery under Sharia. Therefore the Muslim governments didn’t mind if Christian seafarer were enslaved and held to ransom. Rich captives were returned to their families after enormous ransoms were paid but poor captives had to live out their lives as slaves. European governments even paid tribute to Muslim governments so the Muslims would leave their sailors alone.
The USA and Jefferson
Barbary Pirates made slaves of American sailors. Thomas Jefferson the American ambassador to France asked the ambassador from Tripoli "why do you do this" ,and the response was the Qu'ran gives us permission to make slaves of non Muslims. 
At first the United States paid tribute to prevent enslavement of their sailors but then Thomas Jefferson became President. Jefferson didn’t like this as he rightly guessed paying tribute would just lead to bigger and bigger demands.
At first Jefferson reluctantly paid ransom as he could not get together a force large enough to defeat the pirates. Later when the pirate demands became too large he succeeded in waging war against them. After that the pirates left Americans alone but Europeans were still at risk from the pirates.
Back to Europe
During the first half of the 19th Century European nations gradually cleaned up the remaining mess.
Liberals shouldn’t be Pacifists.