Complex sentence: The deaths of a number of senior merchants 1756--61 gave him the opportunity to emerge, and his ability to deliver goods and his skills in creating special long term relationship with foreigners and officials, attracted and retained foreign traders which contributed greatly to his success.
Split into simpler sentences: The deaths of a number of senior merchants in 1756--61, gave him the opportunity to emerge. His ability to deliver goods and his skills in creating special, long term relationship with foreigners and officials, attracted and retained foreign traders which contributed to his success.