The growing popularity of gas light led to competing gas companies, including the Aubin Patent Gas Company and Citizens Gas Company. The San Francisco Gas Company quickly acquired these smaller rivals. However, one rival did provide serious competition. The Bank of California founded the City Gas Company in April 1870 to compete with the gas monopoly held by the Donahue brothers' operation. City Gas began operation in 1872 and initiated a price war with the San Francisco Gas Company. In 1873, the two companies negotiated a consolidation as a compromise and the Bank of California gained part ownership of "the most lucrative gas monopoly in the West". On April 1, 1873, the San Francisco Gas Light Company was formed, representing a merger of the San Francisco Gas Company, the City Gas Company, and the Metropolitan Gas Company.
