Hamad ibn Isa Al Khalifa (1872–1942)

While the Persian Gulf Residency was in charge of the external representation of the Emirates in the Gulf, an advisor was assigned to assist the Sheikh in managing the affairs of his Emirate. In 1926, Charles Belgrave was appointed the government advisor due to the unrest prevailing since 1919 over the application in Bahrain of the civil and criminal laws of the British Raj. Faced with this violence, then Commissioner Sir Clive Kirkpatrick Daly had forced Sheikh Isa to abdicate in 1923. The Raj withdrew Major Daly from Bahrain in 1926 and invited Hamad to take over as vice-ruler and appoint an advisor. Thus, Belgrave helped establish municipal government. Starting as an economic advisor, he soon became a political, military, and judicial one as well, commanding the police, judiciary, health, customers, public works, and parks departments. Although Belgrave's many duties spread him quite thin, he did manage to produce improvements in education, surveying, and internal security, serving until 1957.

During King Hamad's reign, the search for oil began under the aegis of the Bahrain Petroleum Company (Bapco), and in 1932 the first oil well on the western side of the Persian Gulf began production. He had already established the first customs office in Manama as crown prince in 1917, and in 1923 he built a port for 5,000 rupees and appointed British customers officer Claude de Grenier as Director. In 1941, a bridge was opened between Manama and Muharraq Island. Dealing with international conflicts in the region, Hamad developed electricity, water, health, and education in his territory during his reign.[2][3]