Following the First war of Independence in 1857, the British government took direct control of India. Since 1851, gold sovereigns were produced "en masse" at the Royal Mint in Sydney. In an 1864 attempt to make the British gold sovereign the "imperial coin", the treasuries in Bombay and Calcutta were instructed to receive (but not to issue) gold sovereigns; therefore, these gold sovereigns never left the vaults. As the British government gave up hope of replacing the rupee in India with the pound sterling, it realised for the same reason it could not replace the silver dollar in the Straits Settlements with the Indian rupee (as the British East India Company had desired). Since the silver crisis of 1873, several nations switched over to a gold exchange standard (wherein silver or banknotes circulate locally but with a fixed gold value for export purposes), including India in the 1890s.