Is War and Turpentine truly based on Hertmans's grandfather's memoirs?

One thing that's striking about part II (1914-18) of Stefan Hertmans's 2013 novel War and Turpentine, through the entire account of Urbain's experiences in the first World War - in the trenches, in various skirmishes and firefights, wounded and in recovery - there's no mention whatsoever of the cause he's fighting for (or against), of the politics of the era, of the great strategic plans of the generals, of the progress of the war - we know that he's from Flemish area of Belgium, that French is the language of the educated, that he's fighting an invasion of the German army, but that's about it - there's not a moment of reflection on the purpose of the war, on nationalism or patriotism or democracy. And I believe this is an entirely accurate account of war; the ordinary conscripted soldiers such as Urbain (though he is notch above the ordinary, having attended a four-year military secondary school and having shown courage and leadership enough to earn a battlefield promotion)just think day to day about their survival and about food, clothing, shelter (aside from an undifferentiated visceral hatred of the "krauts"). The 80 or so pages are among some of the finest and most gruesome writing about warfare from the soldier's point of view; I wonder while reading it how much - if at all - Hertmans drew from an actual manuscript that his grandfather may (or may not) have prepared. The writing seems far beyond that of the educated amateur - so if it's based on a memoir it's been transformed into a literary work; it's possible that it's all a work of the imagination and that his grandfather never composed a memoir manuscript. As an aside, interestingly (to me), my grandfather in his 50s composed a memoir of his childhood in a shtetl in what today is Ukrainia and his emigration to America in the early 20th century; like Hertmans (not as well that) I polished his manuscript and tried to interest publishers, but there was no market for a memoir unless the author matured into a famous American. Oh, well - I tried. Great to see the success of this beautiful tribute to the lives and accomplishments of another generation, another time.