The French and British armies attacked the German army using the River Somme as the axis of their advance. The battle cost many Allied lives – 57,000 casualties on the first day, including 20,000 killed outright.
In the Summer of 1916, General Haigh, like his predecessor, General French, was pressured by politics into joining the French for an assault along the River Somme, which was the boundary between the French and the British forces. Boundaries are always a vulnerable point in battles and in this case, the German troops were particularly strong, prepared to exploit any weakness and drive a wedge between French and British forces.
The 10th, 11th and 20th Hussars were mounted for this battle, except for a dismounted company of the 20th provided by two troops from each squadron. The first infantry assault, beginning on 1st July 1916, cost the British 57,000 casualties on the first day alone. Haigh kept up the pressure and for some weeks the slugging match continued, with appalling losses on both sides. The cavalry was not used, as the ground was impossible to cross due to the incessant artillery pounding and the heavy rain which turned the ground into a bog impassable to horses.