Complex sentence: In 1727 Balchen was part of a mission to resupply besieged Gibraltar although by the time the fleet arrived the siege had been broken and in 1728 Balchen received promotion to Rear-Admiral.
Split into simpler sentences: In 1727 Balchen was part of a mission to resupply besieged Gibraltar although by the time the fleet arrived the siege had been broken. In 1728, Balchen received promotion to Rear-Admiral.