WW1 was a brutal war and that battle was costly for all.
The Battle of the Somme was one of the costliest battles of World War I. The original Allied estimate of casualties on the Somme, made at the Chantilly Conference on 15 November 1916, was 485,000 British and French casualties and 630,000 German....and a lot of horses.
https://en.wikipedia.org/wiki/Battle...mme#Casualties