That era!

I am reading at the moment The Battle Of The Somme First Phase By John Buchan 1917 1st Ed H/C as I try to get 1st eds where I can afford it.
Anyway there are a few battles of WWI that interest myself apart from that whole conflict but what I came across in this book really took me to what they thought about the war and themselves.
The letter was written by a young officer on the eve of the Somme offensive taking place and illustrates the beliefs he held;
Ad Verbatim;

"I am writing the letter to you just before going into action to-morrow morning about Dawn.
"I am about to take part in the biggest battle that has yet been fought in France, and one which ought to help win the war very quickly. (Still had 2 1/4 years to go my italics)
I never felt more confident or cheerful in my life before, and would not miss the attack for anything on earth. The men are in splendid form, and every officer and man is more happy and cheerful than I have ever seen them. I have just been playing a rag game of football in which the umpire had a revolver and a whistle.
"My idea in writing this letter is in the case I am one of the 'costs', and get killed. I do not expect to be, but such things have happened, and are always possible.
"It is possible to fear death out here when one is no longer an individual, but a member of a regiment and of an army. To be killed means nothing to me, and it is only you who will suffer for it; you really pay the cost.
"I have been looking at the stars, and thinking what an immense distance they are away. What an insignificant thing the loss of, say 40 years of life is compared with them! It seems scarecly worth talking about.
"Well good-bye you darlings. Try not to worry about it, and remember that we shall meet again really quite soon.
"This letter is going to be posted if.....Lots of love. From your loving son.

Qui procul hine
Ante diem periit,
Sed miles, sed pro Patria."

Translated roughly to -
Before that day, at nine killed, the soldiers, but also for the country.

The young officer was killed on the first day of the Somme battle

I think the cause was just and had to be done was the thoughts in their minds and death their constant companion.
This is why I get the earliest books written on battles this one is just 1 year after the event so it cannot really be twisted or fluffed out to suit a writers style.