Private Leslie Friston, who served as a nurse with the Royal Army Medical Corps, was blinded and had respiratory problems after a gas attack in 1917.
As the 23-year-old was recovering in a makeshift hospital bed, a German plane passed overhead and machine-gunned the building’s tin roof.
Two of the bullets struck his soldier’s Bible, which was on his bedside table.
“He said the Bible saved his life as it took the brunt of the attack,” his daughter, Ena Thompson, said.
Mrs Thompson, 87, added: “If the bullets had landed just a few inches further towards him, he would not have survived – and I wouldn’t be here today.”
After surviving the war, Private Friston, from Surbiton in Surrey, brought the Bible home with him. He passed away in 1958.
“He was incredibly lucky and I think he knew this as he kept the Bible with him for the rest of his life,” Mrs Thompson said.
He did not want to talk about his experiences, however.
Mrs Thompson explained: “I used to ask him ‘Would you tell me about the war…?’ and he would say ‘No, I don’t want to talk about it.'”
His sight returned and he ran a grocery store in Hampton, southwest London.
“When I hold the Bible I just get a special feeling. It might sound a bit strange but it makes me feel comfortable and happy.
“It’s a nice feeling that it saved his life. It makes me feel close to him.”
Mrs Thompson was speaking as part of the Royal British Legion’s 2018 Poppy Appeal.
“I am extremely thankful to the WWI generation for all they did for us,” she said.