The Persian Gulf campaign of 1819 was a British punitive expedition, principally against the Arab maritime force of the Al Qasimi in the Persian Gulf, which embarked from Bombay, India in November 1819 to attack Ras Al Khaimah. The campaign was militarily successful for the British and led to the signing of the General Maritime Treaty of 1820 between the British and the Sheikhs of what was then known as the "Pirate Coast", would become known as the "Trucial Coast" after this treaty. Today, the territory comprises much of the United Arab Emirates.

The Al Qasimi is an Arab dynasty in the Persian Gulf that rules Sharjah and Ras Al Khaimah, today forming two of the seven emirates of the United Arab Emirates. They are one of the longest reigning royal families in the Arabian peninsula. Historically, they also ruled over the town of Lengeh as sheikhs for a century until its' annexation by Iran in 1887.