In 1665 England became involved in a war with Holland. The war did not go well, and in 1667 the Dutch fleet defeated the English navy. Charles II feared that a weakened England was now likely to be invaded by the French. For hundreds of years the French were seen as England's main European rivals. One of the reasons for this constant conflict concerned the subject of religion. Whereas England was a Protestant nation, France had always remained loyal to the Catholic faith.
Charles II, afraid that his powerful neighbour might try and invade England, sent his sister Henrietta to talk to Louis XIV of France. In their talks, Henrietta told Louis XIV that Charles II wanted England and France to become allies. Louis XIV replied that he was willing to help England but in return he demanded that Charles become a Catholic. Charles agreed to this but argued that he needed time before announcing his decision to the people of England. Charles feared that the English Protestants might try to overthrow him when they realised that they had a Catholic king.
In 1670 Charles II and Louis XIV signed the Treaty of Dover. In the treaty Louis XIV agreed to give Charles a yearly pension. A further sum of money would be paid once Charles announced to the English people that he had joined the Catholic church. Louis XIV also promised to send Charles 6,000 French soldiers if the English people rebelled against him. For his part, Charles agreed to help the French against the Dutch. He also promised to do what he could to stop the English Protestants from persecuting Catholics.
This treaty was kept secret from the English people while Charles tried to persuade Parliament to become more friendly towards the French government. Charles used some of the money to bribe certain members of Parliament. These MPs, who supported Charles' pro-Catholic policies, became known as Tories by their opponents in Parliament.
However, the vast majority of members of Parliament remained loyal Protestants. When Charles suspended acts of Parliament that punished Roman Catholics, Parliament passed the Test Act in 1673. This act required all government officials to swear an oath that they were Protestants. Several of the king's senior ministers were now forced to resign.
In 1678, Titus Oates, an Anglican minister announced that he had discovered a Catholic plot to kill Charles II. Oates claimed that Charles was to be replaced by his Roman Catholic brother, James. He went on to argue that after James came to the throne Protestants would be massacred in their thousands. This announcement made Catholics more unpopular than ever, and eighty of them were arrested and accused of taking part in the plot. Several were executed before it was revealed that Titus Oates had been lying.
Catholics hoped that Charles would now fight back and attempt to destroy the power of the Protestant church in England. However Charles was convinced that any attempt to do this would end in defeat. Therefore, he waited until he was on his deathbed before he declared that he was a Roman Catholic.