Whatever the diversity of the European armies' component units—and that diversity embraced French Turcos in turban and braided waistcoats, Russian Cossacks in kaftan and astrakhan hats and Scottish highlanders in kilt, sporran and doublet—there was a central uniformity to their organisation. That was provided by the core fighting organisation, the division. The division, a creation of the Napoleonic revolution in military affairs, normally comprised twelve battalions of infantry and twelve batteries of artillery, 12,000 rifles and seventy-two guns. Its firepower in attack was formidable. In a minute of activity, the division could discharge 120,000 rounds of small-arms ammunition— more if its twenty-four machine guns joined in the action—and a thousand explosive shells, a weight of fire unimaginable by any commander in any previous period of warfare. There were in Europe, in 1914, over two hundred divisions, in full existence or ready to be called into being, theoretically deploying sufficient firepower to destroy each other totally in a few minutes of mutual life-taking. The current belief in the power of the offensive was correct; whoever first brought his available firepower into action with effect would prevail.
What had not been perceived is that firepower takes effect only if it can be directed in timely and accurate fashion. That requires communication. Undirected fire is wasted effort, unless observers can correct its fall, order shifts of target, signal success, terminate failure, co-ordinate the action of infantry with its artillery support. The communication necessary to such co-ordination demands, if not instantaneity, then certainly the shortest possible interval between observation and response. Nothing in the elaborate equipment of the European armies of the early twentieth century provided such facility. Their means of communication were at worst word of mouth, at best telephone and telegraph. As telephone and telegraph depended upon preserving the integrity of fragile wires, liable to be broken as soon as action was joined, word of mouth offered the only standby in a failure of communication, consigning commanders to the delays and uncertainties of the earliest days of warfare.
~ From The First World War by John Keegan, p. 21