Complex sentence: In 1835 the firm had commissioned construction of the first merchant steamer in China, the "Jardine", launched a cargo line from Calcutta in 1855 and began operating on the Yangtze River.
Split into simpler sentences: In 1835 the firm had commissioned construction of the first merchant steamer in China, the "Jardine". The firm launched a cargo line from Calcutta in 1855, which began operating on the Yangtze River.