Complex sentence: He joined the Knights in 1876, became Secretary of a District Assembly in 1877 and was elected Grand Master Workman in 1879, at the time the Knights had around 10,000 members.
Split into simpler sentences: He joined the Knights in 1876, became Secretary of a District Assembly in 1877 and was elected Grand Master Workman in 1879. At the time the Knights had around 10,000 members.