There was the belief that you where needed by King and Country to protect the homeland even before the Kitchener posters. I had a great uncle who served in the British Army and was demobbed in 1911, with an education. He went to Canada and worked for Westinghouse as a draughtsman. When war broke out a guy in Canada funded a private battalion to go and fight in the war my uncle joined this battalion and ultimately lost his life, 100 days after being wounded in a big Canadian Battle.
(The story of PPCLI is fascinating) My great uncle was well away from this country he had already done 12 years army service and yet dashed back to protect his country.
I find it unbelievable, living in the 21century, but this was a different time with different attitudes.
Keith