4. Battlefield communications was always a major problem in the First World War. No method was entirely reliable, but good communications were essential. Commanders had to know how the attack was progressing to know where and when to send in reinforcements. The artillery and the front line soldiers had to be in sync about when and where the guns would fire, both to help destroy defences for the infantry and to avoid "friendly fire" deaths.

What's the best way to ensure communication on the battlefield is successful?