Ernest was the son of William and Mary Brooks of Warialda NSW. Although he had previously been rejected, he passed his medical examination at Goondiwindi in September 1917. He enlisted at Toowoomba two days later, stating he was twenty seven years old and employed as a Labourer.
Ernest joined the 25th Battalion, 21st Reinforcement and left Australia on SS Canberra in November 1917. After arriving in England at the end of January 1918 he spent three months training before being sent to France. In June he was wounded in action and invalided back to England where he was treated for a gunshot wound to his knee. Ernest came back to Australia and was medically discharged in February 1919. He returned to Yetman where later that year he married Mary McPherson.
Ernest Books has his name recorded on the Yetman Honor Roll.