The Flowers of the Grass is a series of novels which follows two young German soldiers through the Great War, from the trenches into the air.
Home Before the Leaves Fall is the first in the series. Franz Becker and his friends are studying law at Heidelberg, but when the war starts they hurry to volunteer…
Available as a paperback from Troubadour:
https://www.troubador.co.uk/bookshop/historical/home-before-the-leaves-fall/
and as an e-book from Amazon:
N L Collier 