 In the supplementary Treaty of the Bogue, the Qing empire also recognized Britain as an equal to China and gave British subjects extraterritorial privileges in treaty ports.The US, at the same time, wanting to protect its interests and expand trade, ventured the six hundred miles up the river to Hankow sometime in the 1860s, while the , a sidewheeler, made her way up the river to Yichang in 1874.The first , a sidewheel gunboat, began charting the Yangtze River in 1871.