Sometimes he calls it "a war," as if it were any other war.
Sometimes he calls it "the war," distinguishing it from other, petty, disputes.
Sometimes he calls it "the War," said with an audible capital letter, a proper noun.
Sometimes he calls it "war," an abstract made into a concrete substance, unique, as children speak of Mum or Dad or home.
The definite and indefinite articles, the slight distinction used to play games with himself, to convince himself that it was smaller than he remembers it. But each article merely underlines the headline proclaiming his deeds and the darkness .