Could we all agree on the following statement:

In 1914, many British soldiers (and other citizens, particularly younger ones) were convinced that their country was right to join the war.

(In later years, the percentage dwindled, mainly because there were a lot more British casualties than originally expected. Note that this is not exactly the same as joyfully volunteering, but pretty well correlated. Note also that the same statements are true about most wars and most countries. Take the Vietnam war as another example: in Kennedy's time, only the communists were the villains; later on, the Văn Thiệu regime lost its reputation of sainthood as well, the sole cause being the rising US casualty numbers.)

We may then concentrate on politics.