I find the Great War of ever increasing interest. Much of that war was eclipsed in my early life by the nearness of WWII... and the ensuing movies, etc.

The British Army establishment was quite shrewd in the early days of The Great War and recruited, I forget the exact phrase, "regional regiments" where brothers, cousins, friends and work mates all joined the same regiment. The idea was that peer pressure made soldiers behave better in battle.

Towards the end of the war fresh enlistments were more likely directed to the regiments that had been "emptied" by a great battle.

Of course, these are just my guesses. [I see the reference URL I had to The Great War in the Manx Notebook was just entered earlier so I'll omit it here.]