Answer the question at the end by quoting:

David Gaub McCullough (; born July 7, 1933) is an American author, narrator, historian, and lecturer. He is a two-time winner of the Pulitzer Prize and the National Book Award and a recipient of the Presidential Medal of Freedom, the United States' highest civilian award. Born and raised in Pittsburgh, McCullough earned a degree in English literature from Yale University.
McCullough was born in the Point Breeze neighborhood of Pittsburgh, Pennsylvania, the son of Ruth (nee Rankin) and Christian Hax McCullough. He is of Scots-Irish descent. He was educated at Linden Avenue Grade School and Shady Side Academy, in his hometown of Pittsburgh. One of four sons, McCullough had a "marvelous" childhood with a wide range of interests, including sports and drawing cartoons. McCullough's parents and his grandmother, who read to him often, introduced him to books at an early age. His parents often talked about history, a topic he says should be discussed more often. McCullough "loved school, every day"; he contemplated many career choices, ranging from architect, actor, painter, writer, to lawyer, and contemplated attending medical school for a time. In 1951, McCullough began attending Yale University. He said that it was a "privilege" to study English at Yale because of faculty members such as John O'Hara, John Hersey, Robert Penn Warren, and Brendan Gill. McCullough occasionally ate lunch with the Pulitzer Prize-winning novelist and playwright Thornton Wilder. Wilder, says McCullough, taught him that a competent writer maintains "an air of freedom" in the storyline, so that a reader will not anticipate the outcome, even if the book is non-fiction. While at Yale, he became a member of Skull and Bones. He served apprenticeships at Time, Life, the United States Information Agency, and American Heritage, where he enjoyed research. "Once I discovered the endless fascination of doing the research and of doing the writing, I knew I had found what I wanted to do in my life." While attending Yale, McCullough studied Arts and earned his bachelor's degree in English, with the intention of becoming a fiction writer or playwright. He graduated with honors in English literature (1955).

Did he have any siblings?

One of four sons,

Answer the question at the end by quoting:

David was born on 28 January 1858, in St. Fagans near Cardiff, Wales, the eldest son of the Rev. William David, a fellow of Jesus College, Oxford, a classical scholar and naturalist and his wife Margaret Harriette (nee Thomson). His mother's cousin, William A. E. Ussher of the Geological Survey, first interested David in what was to be his life work. At the age of 12, David went to Magdalen College School, Oxford in 1870. In 1876 he gained a classical scholarship to New College, Oxford.
When World War I broke out in 1914, David was a strenuous supporter of the war effort, supporting the campaign for conscription. In August 1915, after reading reports about mining operations and tunnelling during the Gallipoli Campaign, along with Professor Ernest Skeats, a professor at the University of Melbourne, David wrote a proposal to Senator George Pearce, the Australian Defence Minister, suggesting that the government raise a military force to undertake mining and tunnelling. After the proposal was accepted, David used his advocacy and organisational abilities to set up the Australian Mining Corps, and on 25 October 1915 he was appointed as a major, at the age of 57. The first contingent of the corps consisted of 1,300 officers and men that were initially organised into two battalions before being reorganised into three tunnelling companies, as well as an electrical and mechanical mining company. After departing Australia for the United Kingdom in February 1916, the corps arrived on the Western Front in May 1916. Given the title 'Geological Adviser to the Controllers of Mines in the First, Second and Third Armies', David became relatively independent and spent his time in geological investigations, using his expertise to advise on the construction of dugouts, trenches, and tunnels, the siting of wells for provision of pure drinking water from underground supplies, giving lectures, and producing maps. In September 1916 he fell to the bottom of a well he was examining, breaking two ribs and rupturing his urethra. He was invalided to London but returned to the Front in November, assuming the role of geological technical advisor to the British Expeditionary Force. On 7 June 1917 his wartime contribution culminated in the mining of German positions in the Battle of Messines. In January 1918, David was awarded the Distinguished Service Order and in November he was promoted to lieutenant colonel. The war having concluded, he was demobilised in 1919. He was also Mentioned in Despatches twice.

Was this a military endeavor?
David wrote a proposal to Senator George Pearce, the Australian Defence Minister, suggesting that the government raise a military force to undertake mining and tunnelling.