Complex sentence: A powder magazine was installed in 1789 followed by the Battery in 1791 and constructed under the direction of George Barney, one of Australia's most important Colonial Engineers of the mid 19th century.
Split into simpler sentences: A powder magazine was installed in 1789 followed by the Battery in 1791. The battery was constructed under the direction of George Barney, one of Australia's most important Colonial Engineers of the mid 19th century.