David Langdon was born on September 20, 1840, in Pennsylvania to David and Charity Langdon. His father was a lumberman who owned $5,000 of real estate and $576 of personal property by 1860. He grew up and attended school in Burnside, Pennsylvania.
He enlisted in the Union army on September 10, 1861, and he mustered in as a private in Company D of the 78th Pennsylvania Infantry. The regiment took part in the Battle of Stones River, the Battle of Chickamauga, and the Atlanta campaign. He mustered out on November 4, 1864.
He returned to Burnside after leaving the army, and he married Emily Wilson around 1867. They had at least six children: Howard, born around 1869; Elmore, born around 1872; George, born around 1876; Clara, born around 1879; Mona, born around 1884; and Fay, born around 1884. He worked as a laborer, and by 1870, he owned $100 of personal property. By 1890, he was suffering from lung disease. He applied for a federal pension in November 1890 and eventually received one. By 1900, he was working as a lumberman in Altoona, Pennsylvania. A decade later, he was working “odd jobs.” He died of pneumonia in Altoona on November 18, 1911.