Piracy off the Barbary coast was often assisted by competition among European powers in the 17th century. France encouraged the corsairs against Spain, and later Britain and Holland supported them against France. However, by the second half of the 17th century the greater European naval powers began to initiate reprisals to intimidate the Barbary States into making peace with them. The most successful of the Christian states in dealing with the corsair threat was England. From the 1630s onwards England had signed peace treaties with the Barbary States on various occasions, but invariably breaches of these agreements led to renewed wars. A particular bone of contention was the tendency of foreign ships to pose as English to avoid attack. However, growing English naval power and increasingly persistent operations against the corsairs proved increasingly costly for the Barbary States. During the reign of Charles II a series of English expeditions won victories over raiding squadrons and mounted attacks on their home ports which permanently ended the Barbary threat to English shipping. In 1675 a bombardment from a Royal Navy squadron led by Sir John Narborough and further defeats at the hands of a squadron under Arthur Herbert negotiated a lasting peace (until 1816) with Tunis and Tripoli.