British expeditions to protect their Indian trade routes led to campaigns against Ras Al Khaimah and other harbours along the coast, including the Persian Gulf Campaign of 1809 and the more successful campaign of 1819. The following year, Britain and a number of local rulers signed a maritime truce, giving rise to the term Trucial States, which came to define the status of the coastal emirates. A further treaty was signed in 1843 and, in 1853 the Perpetual Treaty of Maritime Truce was agreed. To this was added the 'Exclusive Agreements', signed in 1892, which made the Trucial States a British protectorate.