"Who'd want that thin irrelevant strip anyway," - asks Musket

I would strongly recommend that you actually read why the Battle of the Somme was fought when and where it was, before asking stupid questions. Here are just a few of the factors:

1: Hundreds of thousands of your allies troops are dying at a place called Verdun - you as an ally have been asked to do something to relieve the pressure on them by attacking your common enemy so that he has to divert resources to defend against your attack.

2: The timing scale and place of the battle designed to relieve the pressure on the French fighting at Verdun were not of Haig's choosing they were imposed upon him by the political leadership of both Great Britain and France.

3: For any attack on the "Western front" to succeed it had to be made against a salient. Attacking any such feature successfully will result in a sizeable retreat and a marked contraction in your enemy's front line.

4: Salients can also be good places to mount attacks from. Had the Germans attacked from the Somme salient and split the British and French Armies then the British would have faced in 1916 exactly what they faced in France in 1940 which resulted in the Dunkirk evacuation.

5: Let's not bother, leave the French to slug it out down at Verdun and we will just sit tight until we are ready? Not a good option as along the Northern part of the Somme salient the Germans held the high ground, where according to their fancy and supply of artillery ammunition they could just sit and blow our troops to bits in target practice.

All extremely good reasons Musket for wanting to take that strip of land away from them. It was French territory, occupied by Germans who had no right being there and the French wanted it back - as their allies we helped them do it, as it was thought at that time that the Germans would not have responded positively to any served eviction notice.

Akenaton is perfectly correct Falkenhayn had started the year 1916 off with "attrition" in mind, his strategy was to bleed the allies white on the western front. By December that year all that strategy had succeeded in achieving was the fatal reduction in the morale and fighting capability of the German Army. The lessons Haig and Rawlinson learned in 1916 ensured victory for the Allies in 1918, and came very close to winning it in 1917.