The existing commercial tensions between England and the Netherlands escalated between 1662 and 1664, involving English provocations in North America and West Africa. Although negotiations to avoid the outbreak of war took place throughout much of 1664, both sides refused to compromise what they considered were their vital interest. In 1664, Lord Arlington, gained royal favour and he and his client, Sir Thomas Clifford M.P., later Lord Clifford, began to cooperate with the king's brother James, Duke of York. They coordinated their efforts to reduce Dutch competition through a policy of reprisals against Dutch ships, and expected significant personal gain from this policy.