Complex sentence: In 1865 the Dock Company got permission to build a westwards extension to the dock--construction began in 1873, with R.A. Marillier as engineer and John Hawkshaw as consulting engineer.
Split into simpler sentences: In 1865 the Dock Company got permission to build a westwards extension to the dock. Construction began in 1873, with R.A. Marillier as engineer and John Hawkshaw as consulting engineer.