Following the signing of the Treaty of Amity and Commerce in 1859, Yokohama was opened as a port for foreign trade and quickly grew in importance. Through the New Currency Act of 1871, Japan adopted the gold standard along international lines, with 1 yen corresponding to 1.5g of pure gold. Silver coins were also issued for trade with Asian countries who favoured silver as a currency, thus establishing a de facto gold-silver standard. However, inflation caused by the 1877 Satsuma Rebellion and the outflow of a large amount of silver due to increased imports, a large discrepancy arose between government-issued banknotes and specie coin. This became a source of trouble for the merchants in Yokohama, as specie rather than banknotes came to be demanded for foreign trade. On 28 February 1880, a syndicate of 22 people with the support of Fukuzawa Yukichi and Inoue Kaoru established a bank in accordance with the National Bank Act to ensure the availability of specie for the trading community. The bank had an initial capitalization of three million Yen, of which one million was invested by the Ministry of Finance. The bank was modeled after the Hongkong and Shanghai Banking Corporation, which had a great influence on Japan's overseas trade and foreign exchange at the time. A branch office was opened in Kobe later the same year.