Complex sentence: Rats had been seen moving away from the German trenches, which was inferred to be due to leaky gas cylinders; the systematic bombardment of British defensive positions and the testimony of the deserter led Lieutenant-General C. T. McM.
Split into simpler sentences: Rats had been seen moving away from the German trenches, which was inferred to be due to leaky gas cylinders. The systematic bombardment of British defensive positions and the testimony of the deserter led Lieutenant-General C. T. McM.