Complex sentence: On 13 August 1914,2,3, and 4 Squadrons, comprising 60 machines, departed from Dover for the British Expeditionary Force in France and 5 Squadron joined them a few days later.
Split into simpler sentences: On 13 August 1914,2,3, and 4 Squadrons, comprising 60 machines, departed Dover for the British Expeditionary Force in France. The 5 Squadron joined them a few days later.