A fascinating coda to the tale of Wellington’s most useful intelligence officer, Lieutenant-Colonel Colquhoun Grant, during the Peninsular War suggests that but for an incompetent Prussian cavalry general, Napoleon would likely have been defeated at the Battle of Ligny, thereby rendering the historic battles of Quatre-Bras and Waterloo entirely unnecessary.
It will scarcely be believed that this resourceful man was back in the Peninsula by September and reported himself to Wellington just four months after he had been captured near Sabugal. His chief got him a brevet-colonelcy without delay, and employed him as his head Intelligence officer during the remaining eighteen months of the war.
He was again called out during the Hundred Days from the Military College at Farnham, where he had been given a berth as instructor in 1814, and was put by Wellington in charge of his Intelligence department in Belgium. He always maintained that the surprise of the British and Prussian armies by Napoleon on June 15th would never have taken place but for the stupidity of a cavalry brigadier, who stopped one of his emissaries bearing certain news of the outmarch of the French army. Grant’s messenger was detained by the Hanoverian general Dõrnberg, whose cavalry was watching the frontier about Tournai and Mons. He did not send him on till the fighting had already begun around Charleroi, and Grant could only deliver the message to Wellington a day late, when the Battle of Quatre-Bras had actually begun. The loss of the twenty-four hours was almost irreparable: if Dõrnberg had not stopped the all-important news, Wellington’s whole army would have been concentrated a day earlier than was actually the case, and he would certainly have co-operated with Blücher at Ligny, instead of being forced to hold back Ney at Quatre-Bras with detachments that kept dropping in all through the day.
History repeatedly teaches that having the wrong man in the wrong place at the wrong time is one of the most costly mistakes that any leader of any sort of organization can make. The consequences are often not merely limited to immediate failure, but result in complete catastrophe and an existential crisis for the organization.
In this case, more than 20,000 British and Prussian soldiers were killed or wounded unnecessarily, due to the unnecessary action of a single officer.