The Battle of Somme was an offensive campaign lead by the British and French forces against the German Empire. While this resulted in the British and French's victory, it came at a hefty price. The Battle of Somme lasted over four months, with well over a million soldiers wounded or killed in the process on both sides.
Why Include It?
The Battle of Somme was the first instance of a tank being used in warfare combat. What more of a reason do you need to include this fight in the next Call of Duty? Granted, this battle could very well be in Battlefield 1 as there are similar tanks included in the trailer, but there's always more than one way to take a perspective on one of the bloodiest battles in World War I.