I'm sure there were lots of reasons Les. Many of which were opportunity. To the Victor the spoils.

In terms of why didn't soldiers question, well the Edwardian fascination with jingoism for starters. Empire day celebrations were the order of the day.

If soldiers did start questioning the government ensured there were enough padres in soldier's uniforms to let them know God wants us to win.

This appalling association between religion and carnage carried on and of course still does.

The second world war,
It came and it went.
We forgave the Germans
And now we are friends.
Though they murdered six million
In the ovens they fried.
The Germans now too have
God on their side.